Good Morning, Vietnam Directed by Barry Levinson At the Janus Theater

VAUNTED by some as the project which will finally make Robin Williams a truly big star, Good Morning, Vietnam concerns the misadventures of Armed Forces Radio disc jockey Adrian Cronauer, who is stationed in Saigon as U.S. involvement escalates in 1965. An iconoclast whose humorous broadcasting style has won him the admiration of the common grunts and the top brass alike, Cronauer must nevertheless face the displeasure of his immediate superiors as he tries to bring truth, integrity, and rock n' roll to the fighting men of 'Nam.

Anyone who was on hand for Williams' stand up performance at the Lampoon Comedy Night two years ago will be well aware that his manic comedic talents are nothing short of inspired. In front of an audience the quiet, mild-mannered Williams of private life becomes transfigured into a comic dervish, wildly improvising on audience suggestions in a combination of ultra-free association and vocal impersonation that works quicker than the eye can catch.

THE REASON that Good Morning, Vietnam has been billed as such a perfect vehicle for Williams is that a sizable portion of the film is taken up by his on-air improvisational monologues. It is said, in fact, that once the Williams magic was set to work in front of the camera, he was virtually unstoppable: of the original script for the Cronauer broadcast-booth sequences, only one line eventually made it onto the screen.

The problem is that Williams-in-a-broadcast-booth is a far cry from Williams-in-front-of-an-audience. The spontaneity, the timing--everything--is different. In a recent interview Williams said that during the filming in Thailand a group of American expatriate women were on hand in a nearby sound booth, their reactions piped into an earphone Williams wore out of camera shot. This arrangement, it was hoped, would inject some vitality into the bloodless recording sessions; but in the end the plan was abandoned, as it ruined Williams' timing.

While the result is a far cry from live, Williams' routines are more entertaining than most A.M. banter. But even so, the rest of Good Morning, Vietnam is incongruous enough with the comedy sequences that, taken as a whole, the film is difficult to digest. Director Barry Levinson, ecshewing the by-now-traditional shots of Vietnamese villages being burned and peasants shot, intersperses the Saigon sequences with dream-like footage of patrol boats cruising, soldiers milling about, helicopters taking off.

WHILE he was no doubt astute in avoiding cliche, the surrealism of these scenes detracts from the power of their subject. And a difficult-to-fathom subplot involving an unrequited romance with a Vietnamese woman adds neither heat nor light to the production. Levinson has, in fact, included more subplots than sense; too many characters are brought on screen for anything to be resolved, and when the film ends--in an utterly predictable way--the audience would be left with a lot of questions, if it cared enough to ask.

Good Morning, Vietnam is not a bad film, but it's one that falls far short of what its premise and cast might have produced. Unless you're a real die-hard Williams fan, my advice is: pull out.