AS AMUSEMENT FARE, An Evening of Bernstein is like a wildly assorted selection of leftovers from a good French restaurant. This smorgasbord is better and by far more interesting than what is usually served around Harvard; each dish by itself would be quite delicious. But some bits seem stale, there isn't really enough of any one thing, and the subtle flavors of some concoctions are drowned by the stronger flavors of others.

The Evening consists of two courses: antipasto--"A Broadway Revue," and entree--"Trouble in Tahiti," an opera in seven scenes. The general success of the menu is due to the remarkable quality of its five major ingredients: Carol Flynn, Greg Smith, Mike Dineen, Peter Ives, and last--as befits the prima donna--Wendy Shattuck.

The first section of Evening seems designed to exhibit the considerable vocal talents of the five members of the cast. "The Revue" includes such Bernstein greats as "Wonderful Town," and "Tonight." All are sung competently; some--notably "There's a Place for Us," sung by Shattuck and Dineen, and "Unless There's Love," done by Dineen alone--are savory versions of often overdone pieces. Shattuck, a recent graduate of the New England Conservatory, sings magnificently from her first note on; physically small, she is vocally head and shoulders above anyone else on stage.

Unfortunately, this Bernstein is rather deja vu, especially since almost all the songs in the "Revue" were performed in An Evening with Comden and Green, which had two runs at the Loeb earlier this year. An Evening of Bernstein passes over the contributions of his two collaborators, putting an unjust emphasis on Bernstein's lyric-writing genius. On the whole, this Evening at the Agassiz suffers from the inevitable comparison with Comden and Green. The two professionals knew how to put songs and patter together in a continuum; they had the ability to make the most rehearsed gesture appear spontaneous. But the spoken interludes in An Evening of Bernstein are only too obviously filler between songs. The audience--and probably the cast as well-will wish them over soon. Flynn and Smith are especially poor actors; apparently unaware of the meaning of their speeches, they flap their hands, grin fixedly, and fail to enunciate. Ives is saved only by the humor in his lines and his basso profundo. The set--which seems designed to test the cast's mountaineering ability--does not lessen the stiffness of the dramatics, the accompanists are pedestrian. But Ellen Wasserman's lighting, which unobtrusively creates the familiar context of the songs through connotations of color and brightness, makes the production move more smoothly.

The second act of Evening exemplifies the product of too many cooks. Both orchestra and singers give outstanding performances; indeed, the instrumentalists in particular distinguish themselves. Unfortunately, the two don't engage in a cooperative harmony but rather in a duel to the death, voice versus instruments. Such an unequal contest can have only one result. Not even Shattuck's soaring soprano can overcome the determined opposition of the cymbals--especially since their frequencies are very close. Part of the problem is the thick-textured score, with its constant cacophony and acoustical fireworks; part of the trouble is the structure of Agassiz, which lacks a pit or shell to muffle the orchestra. Still, director Leslie Koenig and musical director Ken Getz should have worked out some compromise so that the audience could hear the lyrics as well as the music.

Not that the lyrics are that memorable. Indeed, if the first half of Evening sags occasionally because the songs are such greats, the second half has exactly the opposite problem. With the exception of "There's a Garden," these songs are deservedly obscure. Trouble in Tahiti tries to make suburban life operatic and raise the petty boredom of a failing middle class marriage to the level of tragedy. But any potential for opera sinks soon and swiftly: Why shouldn't this marriage fall apart, and who cares anyway? Bernstein offers us no special reason to care, the characters remain cardboard stereotypes and their situation all too familiar banality. Bernstein's inability to musically activate this trite scenario becomes obvious at the climax, when the characters lapse into speech. If husband and wife had sung these commonplaces of insult and apology, it would have been laughable; their situation doesn't warrant the dignity of music. Even "Island Magic," the cheap illusions of a Technicolor movie, which Bernstein invokes to resolve the couple's muddle (it doesn't deserve to be called dramatic conflict) can't pull off the trick.

But the quality of Grant-in-Aid's production almost transcends all the limitations of space, score, and concept. Shattuck and Ives act well and sing excellently, the Trio choruses an amusing accompaniment, and one can't be bored by the band. The vertical divides of the set work for this latter part of Evening, permitting rapid changes of scene by shifts of lighting. A revue of popular songs and a small-scale operetta by a famous composer are far from risk-free recipes for success, yet despite this Evening's unevenness, one leaves savoring a taste that lingers. For that, Grant-in-Aid nearly deserves a Cordon Bleu.