Johnny Depp is amazingly adept at re-creating the almost forgotten art of pantomime slapstick, a la Buster Keaton and Charlie Chaplin. He's also the main reason to see "Benny & Joon," the latest in a long string of Hollywood movies to blithely suggest that mental illness can be fun.

With a more serious edge than some of the more recent entries in this genre ("Crazy People," "The Dream Team"), and certainly as blatantly sentimental as the worst of them, "Benny & Joon" tells the story of a brother and sister, Benny and Joon Pearl (Aidan Quinn, Mary Stuart Masterson), who must come to terms with the diagnosed schizophrenia of the latter.

Quinn is very good as Benny, the put-upon older brother who runs an auto-repair shop but who has neglected his own personal life for 12 years in an effort to keep Joon stable and out of an institution.

Masterson is even better, seemingly "normal" most of the time, though she occasionally has spurts of erratic behavior — going out into the street to direct traffic, starting little fires around the house, etc.

And there's a bevy of enjoyable character players in supporting roles — Julianne Moore as a waitress/actress who becomes romantically involved with Benny, Oliver Platt as one of Benny's mechanics, C.C.H. Pounder as Joon's psychiatrist and Dan Hedaya and Joe Grifasi as Benny's poker buddies (whose unique take on playing the game is a highlight).

But the subtle scene-stealer here is Depp, as Sam, an illiterate and quiet old-movie addict and ardent admirer of Buster Keaton. Sam has been shuttled to his reluctant cousin's house until Joon wins him in a poker hand. (Or, more accurately, she loses the hand.)

Sam predictably turns Benny's household upside-down and, of course, falls in love with Joon. (The uncle is quickly dropped.)

"Benny and Joon" is one of those forced eccentric comedies (full of literary and cinematic references and an interesting way to make grilled cheese sandwiches) that tries a little too hard to be charming and off the wall. But Depp is affably endearing and offers some hilarious, seemingly impromptu tributes to Chaplin (in a restaurant scene he re-creates the dance of the rolls from "The Gold Rush") and Keaton (a showstopping series of sight gags in a park). His graceful movements as he performs these silent movie slapstick routines and his gentle, sweet demeanor handily steal the film.

Best verbal exchange: Benny asks Sam after his demonstration in the park, "Did you have to go to school for that?" "No," Sam replies, "I got thrown out of school for that."

After "Edward Scissorhands" and "Benny & Joon," Depp has proven himself an actor with much more to offer than his early roles (in "A Nightmare on Elm Street" and TV's "21 Jump Street") might have suggested.

"Benny & Joon" is rated PG, though it does contain some violence, sex and profanity.