True to its word, the San Francisco Symphony's New and Unusual Music series unveiled something partly new and certainly unusual at Davies Hall Friday night.

Some were appalled by the prospect of it all. Others were amused. All were curious to hear the world premiere of "Plump Jack" by one Gordon Peter Getty struggling composer and also perhaps the richest man in America.

Struggling? Well, given the handicaps of; 1). being the youngest son of a legendary, fabulously wealthy, ruthless tycoon; 2). a reputation as a generous benefactor of the arts; 3). willing to undergo the risk of not being taken seriously as an artist because of the above, Gordon Getty has a lot of strikes against him.

But let's forget about the name Getty and take this 57-minute so-called concert opera at face value, rather than name value. And you know "Plump Jack" is not bad.

The title is a good-natured nickname for the aging, portly knight, Sir John Falstaff. Shrewdly, perhaps, Getty chose to set four Falstaffian scenes from Shakespeare's "Henry IV and V" rather than compete with Verdi's formidable setting of "The Merry Wives of Windsor."

Getty claims that his idioms of choice were Richard Strauss and Verdi, but what actually comes over loud and clear is Benjamin Britten. You can hear it in the extended unaccompanied vocal passages, the understated march in Scene IV, the spare, cryptic, sometimes humorous underpinning by the orchestra.

Yet this music has its own eclectic personality, full of unpredictable quirks and flashes of imaginative color. Getty wouldn't be mistaken for a flaming member of the avant-garde, nor is he a memorable tunesmith, but he holds one's interest with his bag of accessibly tonal tricks. If the gut question of the moment is; would we want to hear more from this composer, the answer would be an unhesitating yes.

There are, however, serious problems with the dramatic structure of this piece. The four sections the first three of which were performed separately on previous occasions do not fuse together; the storyline is episodic, the crucial confrontations diffusely molded. After you get over the shock of realizing that Getty actually has some talent, the first two scenes build a sense of anticipation that the final two could not fulfill.

Getty's "opera" certainly received a sympathetic performance from Andrew Massey and the alert San Francisco Symphony. John Del Carlo made a youngish but authoritatively resonant showing as Sir John Falstaff, and tenor Paul Sperry could expertly point out the words in the parts of Prince Hal and later, King Henry V.

This being a concert performance, the singers had little stage business beyond entrances and exits, and an uneasy spotlight shone upon Sperry when he entered as Henry V. Also the laughing (on cue) San Francisco Symphony Chorus clambered noisily and confusingly onstage in Scene III.

At the close of his work, the grinning, shy, curly-haired Getty took some curtain calls, clapping in a compulsively mechanical manner. The applause, though, was not exactly tumultuous.

Is financier Gordon Getty a worthy composer of serious music? Yes, indeed.

Is he a musical dilettante? No.

Is his piece of musical theater, "Plump Jack," dramatically viable? Absolutely, though it rambles even more than Falstaff himself.

Is Getty an orchestrator? No question, yes.

But would all-Getty evenings such as the San Francisco Symphony's Friday night concert take place if he were not one of America's wealthiest men and leading philanthropists? Very doubtful.

A Getty program comes with a built-in budget, a built-in audience, a built-in celebrity and some voyeurism akin to watching "Lifestyles of the Rich and Famous."

My Number One recollection was not of music from this "concert opera," but of Getty on stage at the end of the Davies Symphony Hall concert, before a three-quarters filled house. The tall, lean, 53-year-old was like a jubilant but inhibited high-schooler, applauding back vigorously to the standing ovation made up of his guests, well-wishers, critics and a generous number of unrelated and elated ticket-buyers.

Getty is genuine, and so is his music. But where he is personally charming, his "Plump Jack" is introverted, both in a strangely naive way.

He gave the fat knight Falstaff the lean treatment musically, doing what Shakespeare never succeeded in doing: serving up a long but skinny Falstaff.

''Plump Jack" spreads out Falstaff texts in an overly elongated way, with recitative-like singing that you can understand much of the time. Getty puts these solo recitations at the very core, surrounding them with highly effective orchestral gestures and punctuation that do not blur intelligibility.

He is thoroughly tonal, no more modern in sound than Modeste Mussorgsky or Benjamin Britten, and not inclined to copying recognizable styles of past masters.

His design is no more economical than Shakespeare's. His hourlong piece has no less than 13 solo parts, taken by seven singers. With such copious forces, duets and ensembles (and spirited arias) would have been effective musical devices. But Getty decided to forgo them. In addition the large symphony chorus is required briefly for Scene 3. And though a large orchestra with much percussion is called for, 90 percent of it appears to be maintaining a silent vigil at any given time in his Spartan score.

A greater failing is the excessive length, with little contrast. In single scenes, Getty can be marvelous. One scene -- Falstaff's rebuffed meeting with the new authoritarian king, formerly the drinking buddy Prince Hal -- is prime stuff of opera. It comes complete with an authentic ancient church chant appropriate to the very day on which the real-life Prince Hal had been crowned. Another effective quote is Big Ben's ominous chime when Falstaff's advanced age is revealed.

The Santa Clara University concert of "Plump Jack" in April ended with this scene. Getty's recent completion, with Scene 4, weakens the work. The Hostess' endless recitation about the death of Falstaff is anti-climactic, and the scoring here proved even lighter than the music that had gone before.

The largest work that Getty has attempted, "Plump Jack" is a viable effort with expected miscalculations. It can be deliciously ironic as it calls for harpsichord to portray the fussiness of the fat knight, or for a delectably simulated bagpipe (with oboe and English horn) for Bardolph's exit, or for plucked strings to echo Falstaff's wink.

Of particular note Friday night was the semi-staging. An unruly chorus entrance suggested a noisy coronation crowd, and the newly crowned king sang imperiously in the terrace seats high above stage for Falstaff's banishment.

Where Verdi used comedy (and revised text) to skewer Falstaff in his opera taken from "The Merry Wives of Windsor," Getty went directly to three of the "King Henry" plays to treat Falstaff with greater deference and fewer subplots. The results were mixed. Getty's style is closer to neoclassical, stiff-upper-lip English opera than anything in Verdi's Italian milieu.

The nearly all-male cast was excellent, sparked by a bulbous John Del Carlo in the title role, the clear-cut lyric tenor Paul Sperry as Prince Hal, and Opera San Jose's softer- contoured lyric tenor Michael McCall in multiple supporting roles. The symphony and chorus were very effective under Andrew Massey's sympathetic leadership.

Will "Plump Jack" thrive elsewhere? Perhaps, given enough of a budget.

A bigger question is whether this orchestra or the San Francisco Opera is willing to invest similar resources for premieres by impecunious but ingenious area composers, of whom there are many, none named Getty. Such ventures could halt the snide cracks about checkbook premieres and purchased performances that may still be echoing around Davies Symphony Hall.

With the completion of the fourth and final scene of his concert opera about Falstaff, ""Plump Jack,'' and the premiere of the complete work Friday night in Davies Symphony Hall by the San Francisco Symphony and its chorus and several superb soloists, Gordon P. Getty has good reason to be satisfied, and looked it, as he stood with the performers on the platform, clapping for them with the audience.

He is also faced with a pleasant but difficult question: What now? ""Plump Jack'' in this form is a success on its own terms, and I would guess it is going to be given quite a few performances. The European premiere, by the BBC Philharmonic in London's Royal Festival Hall, is already scheduled for July 19. But as effective as it is in tracing a kind of outline of the story of Shakespeare's fat and rascally but appealing knight, from his pinnacle as the drinking companion and reprobate mentor of Hal, the wild son of King Henry IV, to his rejection and eventual death, ""Plump Jack'' leaves us wishing we had more. These are glimpses -- well-chosen and telling in their effect, but glimpses -- of one of Shakespeare's most memorable and original creations. In about 65 minutes of music, they tell us about him well enough to wish the composer would give us something like the whole picture.

Following the course of ""Plump Jack'' as it has developed over the last two years has also been an interesting study in the character and effectiveness of the score. From the beginning, with Scene 1 as done by the San Francisco Symphony two years ago, it was clear that the orchestra would function in an unusually important way, as a kind of Greek chorus reacting to and commenting on what was being said. With the addition of Scenes 2 and 3, at Santa Clara University last April, Getty's handling of the orchestra seemed more various; individual instrumental voices were speaking out as much as the full orchestra. And the chorus now entered the picture, not only singing but furnishing the hubbub of the crowd at the coronation of Hal as King Henry V.

Scene 1, in the tavern early in ""King Henry IV, Part 1,'' has Hal and Falstaff taking turns pretending to be Hal's angry father. Scene 2, from ''King Henry IV, Part 2,'' shows us Falstaff gulling the fatuous Justice Shallow and then, in a scornful soliloquy, denouncing his lying, boastful ways. Scene 3, longer than the others, is the bitter, humiliating public rejection of Falstaff by the newly crowned King Henry V. Friday night, it was clear that this scene, given excitement and atmosphere by the orchestra no less than by the crowd, and framed beautifully by Gregorian chant authentic to the occasion, is the most powerful and interesting of all.

But Scene 4 turned out to have power of its own. It is the scene from ''Henry V'' in which the death (in bed) of the old knight is described to his longtime confederates by Mistress Quickly, called here Hostess, who ran the Boar's Head tavern and waited in vain for 29 years for Falstaff to marry her. Like the three previous scenes, this one finds its climax in one long speech, and mezzo soprano Clarity James, singing in rich, tender tones, made the moment both beautiful and real by the conviction of her performance. The orchestra, which had reacted to the word ""dead'' in a heartbroken fall of strings, followed her with a commiseration of single instrumental voices. When she said goodbye as Pistol and the others went off to war in France, her ''Farewell! Adieu!'' was clearly addressed to the spirit of Falstaff, and with a whispering snare drum and a long, soft note in the deep strings, the orchestra added its own valedictory.

Now seen whole, ""Plump Jack'' fulfills the promise of its partial performances. What seemed strong before -- especially Scene 3, which is very close to being real theater and not concert theater, what with the crowd and the chant and the ""Hymn to St. George'' and the denunciation of Falstaff by the new king, delivered from the balcony near the orchestra -- seems even stronger.

A fundamental problem also appears. The music the orchestra plays in ''Plump Jack'' is at least as interesting and meaningful as what is sung, but it often constitutes an interruption of the dialogue. This won't do if Getty ever tries to turn the work into a theater piece; in fact, there were times Friday, partly due to some unwise stage direction, when the orchestra's comments, by spacing out the dialogue with unnatural pauses, took away some of the theatrical effect of the scene. Even if ""Plump Jack'' remains a concert opera, it's a problem that should be dealt with.

The performance, conducted by Andrew Massey, was first-rate. Bass-baritone John Del Carlo seemed an ideal Falstaff -- big, rotund of voice, imposing in manner, a real presence in both the flavor and the intellect of the character. Tenor Paul Sperry delivered Hal -- especially the denunciation -- in burningly clear, felt terms. James was an equally ideal Hostess, tenor Michael McCall was a satisfyingly strong Shallow, bass-baritone Arnold Voketaitis sang Pistol with authority, and Peter Lightfoot showed an excellent voice in several smaller roles.

Friday night in Davies Hall it was a heartwarming, only-in-America story. An ordinary man was propelled to the heights where only a few of the top talents visit, and one in a million remains to dwell. It was as though a plain actor had been elected president.

It was Gordon Getty, just a regular San Francisco citizen with modest musical training, feted by the San Francisco Symphony and his peers at a well attended world premiere of his concert opera, "Plump Jack," on the Symphony's New and Unusual Music series....

What of the music, what of "Plump Jack" that the audience seemed to like a lot? It was music that its first listeners could understand instantly, every whit and jot, effortlessly. Nor did they need be concerned that there might be more beneath the surface to hear and to consider. They didn't even need to follow the texts of the four scenes: Shakespeare's "King Henry IV, Part One, Act II, Scene 4; Part Two, III, 2, and V, 5, and "King Henry V," II, 3.

It was mostly accompanied recitative in one-, two- and three-part writing. The orchestra, with a selective choice of its instruments, followed under the voices in a discreet kind of scenic background, pointing up the action and mood described.

The singers did well projecting and characterizing their roles, taking full advantage of the vocal gratefulness of the writing. Getty has done some singing, is a longtime opera devotee and knows what for he is writing. The ensembles are modest to a fault. So is the part for the chorus (a monk's plain chant, a coronation welcome hymn, some crowd noise and commotion).

The four scenes describe Falstaff's downfall. The first is the Falstaff-Prince Hal dialogue in which each, in turn, impersonates Hal's father, Henry IV, on the subject of Falstaff himself. We heard this scene performed by the Symphony in March 1985. Next comes Falstaff's plot to fleece the justices, Shallow and Silence. Part II begins with the devastating rejection of Falstaff by Hal, the newly crowned Henry V, and finally the description of Falstaff's death by the tavern hostess, Nell Quickly.

Everything meaningful in the score is for the voices and carried nicely by them. No arias however. None at all. The music otherwise is a hand-over-hand setting, its continuity following the text, utilizing a minimum of recurrent motivic material in the spare recitative support. There were some high duetting trumpets, after Britten's "Billy Budd," associated with the coronation scene, French horns in a hunting theme, a brief motive for English horn. Otherwise, the musical ideas and color changes came and went with much use of harps, the chimes, later the timpani. In the parts that sounded like Prokofiev, the tuba figured largely. There were some distant suggestions of Strauss, but these more involved passages were brief.

Andrew Massey, the symphony's associate conductor, led a good performance, preserving the score's transparency. As before, in March 1985, Paul Sperry was a fine and lively Prince Hal, singing musically in his distinct and clear tenor. As Henry V, he entered at the Terrace level and slowly descended to the railing to address his rejection to the "Fat Knight." Bass-baritone John Del Carlo was once again splendid as Falstaff, developing the later fall from grace with touching solemnity.

Mezzo soprano Clarity James sang the Hostess with a certain charm and fine restraint in the sadness of her narrative. Tenor Michael McCall sang the Bardolph and First Groom, coming through nicely eventually. Bass-baritone Arnold Voketaitis gave a dignified account of Pistol. Baritone Peter Lightfoot did creditably in the brief roles - cameos - of Silence, Nym and Second Groom. The Symphony served effectively, as well it might.