"Celebrity" opens and closes with a shot of the word "Help!" spelled out by a skywriter above Manhattan. After this ramshackle film and last year's uncomfortably self-referential "Deconstructing Harry," I wonder if Woody Allen has reflected on the very public mess he has made of his life and is at last crying out for assistance.

"You can tell a lot about a society by who it chooses to celebrate," says Judy Davis, providing a handy Cliffs Notes summation of the film's message for those viewers who may have nodded off. Thirty years ago, the statement might have been profound, but after countless examinations of the Western world's obsession with celebrity, the line merely serves as an indicator of just how clueless Allen has become.

"Celebrity" follows the lives of a pair of neurotic New Yorkers (what a surprise!); struggling writer Lee Simon (Kenneth Branagh) and his ex-wife, former schoolteacher Robin (Judy Davis). As Woody's surrogate, Branagh does an adept, and often irritating, impression of Allen, reproducing every gesture, stammer and tic. In standard Allen fashion, Lee is a whiny womanizer seemingly incapable of maintaining an honest, monogamous relationship. When not occupied with skirt-chasing, he plays sycophant to various big shots, peddling a screenplay about an armored-car heist.

Meanwhile, the high-strung Robin makes tentative stabs at changing her life, traveling from a religious retreat (the priest is a television celebrity) to a high-profile plastic surgeon (he's followed by a TV crew after being christened "the Michelangelo of Manhattan" by Newsweek). Eventually, she hooks up with a television producer (Joe Mantegna) and becomes an on-air reporter, achieving her own celebrity status.

Lee and Robin's mid-life crises serve as the framework for a series of sketches; some quite funny, some very flat and none particularly insightful. There's a hilarious backstage scene at a daytime talk show, where gangsters, religious figures and neo-Nazis comfortably mingle, complaining about their agents while hovering around the buffet table. "What is this," says a rabbi in mock chiding tones to a group of jack- booted thugs, "did the skinheads eat all the bagels?"

One of the film's best sequences involves Leonardo DiCaprio, playing a pampered young superstar given to hard-partying and violent outbursts. Even as the police are arresting him for trashing a hotel room and terrorizing his date, Lee pitches his script to the glib bad-boy. Thanks to the kid's celebrity status, the charges are hastily dropped and Lee is swept away to Atlantic City with Leo and his entourage, where he continues trying to insinuate himself even as Leo urges him to join in a drugged-out orgy. DiCaprio is excellent as the self-absorbed hedonist, by the way, using a non-stop stream of compliments and commands to manage those around him.

Unfortunately, for every vignette that works, there are two that don't. One of the worst comes when Robin, believing that her Catholic guilt has made her less than satisfactory in bed, asks an upscale hooker (Bebe Neuwirth) for lessons. After a extremely funny exchange ("What do you think about during oral sex?," asks Neuwirth. "The Crucifixion," answers Robin), the scene degenerates into a tired let's-use-bananas-to-practice- blow-jobs routine. Apparently, Woody Allen missed "Fast Times At Ridgemont High" and all the other comedies that have used the same bit.

A high-school reunion scene with Lee falls just as flat, with the writer making contemptuous observations about his fellow classmates before declaring, "Ask not for whom the bell tolls -- or more accurately, for whom the toilet flushes." It's hard to imagine those words coming from the pen of the man who wrote "Annie Hall."

Beyond the hit or miss nature of the comedy and the discomfort of watching Kenneth Branagh do a two hour Woody Allen impression, the biggest problem with "Celebrity" is that the concept, as well as Allen's shtick, are so very tiresome. After a while, the quips and tart exchanges degenerate into mere chatter as the film drags on for what seems like forever. Even the impressive mega-cast (stand-outs include DiCaprio, Neuwirth, Winona Ryder, Charlize Theron, Melanie Griffith, Famke Janssen, Bebe Neuwirth, and Michael Lerner) can't compensate for the lazy writing, haphazard style and wearying been-there-done-that nature of the black and white movie. "Celebrity" is Woody Allen's 27th feature. Hopefully, he'll wait until he has something new to say before doing his 28th.