"17 Again" has a pretty original take on the "do-over" comedy -- you know, where someone, invariably a male, gets to go back in his life to do-over a key moment or event that continues to bug him. The twist here is that Mike O'Donnell doesn't really go back in time: He is simply 17 again, the point at which, he figures, his life went south. So he winds up in high school with his own daughter and son, and his estranged wife can't understand her weird feelings for this guy who reminds her so much of her ex when he was young.

This film, written by Jason Filardi ("Bringing Down the House") and directed by Burr Steers ("Igby Goes Down"), works better than you might imagine at times but stumbles awkwardly other times. The unevenness in the writing is matched by directorial overkill in certain comic sequences.

Warner Bros. has achieved high awareness for this Zac Efron teen comedy from New Line so that the film could open at No. 1. Boxoffice has mid-range potential.

The film begins when Mike (Efron) really is 17, back in 1989, when he is a high school basketball star with a bright future and hopes for a scholarship. Just before the game where a college scout has shown up, his girlfriend Scarlet tells him she's pregnant. So he throws away everything to marry Scarlet.

Why the filmmakers believe college basketball and parenthood are mutually exclusive is unclear -- are they aware how many student-athletes have families? -- but anyway, it's 20 years later and Mike, played by Matthew Perry, is a walking train wreck. His kids hate him, his wife (Leslie Mann) is divorcing him and his job disappears. Only his best friend, former school nerd-turned-software tycoon Ned (Thomas Lennon), can tolerate his company.

Along comes, as happens in do-over movies, a mystical figure, invariably in a white beard, who grants the downfallen hero his request -- in this instance, to be 17 again. The nice twist to Mike becoming a "fake teen" is that this situation doesn't so much give him a chance to re-shape his life as to help out his daughter (Michelle Trachtenberg) and son (Sterling Knight). He can dispense advice and guidance from the perspective of an adult but in the guise of a schoolmate.

Sequences involving a school bully -- who, the father discovers, is terrorizing his son but dating his daughter! -- and his wife, now 20 years his senior, click pretty well. But the film gets into tonal problems when Steers and Filardi feel the need for the kind of exaggeration believed necessary for teen comedies. Lennon's extreme geek would be funny, quite funny in fact, in the right film but here his performance jars. There is also too much sentimentality thrown in as if the filmmakers don't trust their young audience to get the message.

Efron does a fine job in letting the older man seep through his boyish exterior. As the siblings, Knight and Trachtenberg each have moments when they shine, especially when the daughter starts to think her father is hot, not realizing, of course, that he is her father. Mann, as always, is very funny and gets to put an edge of vulnerability into her performance.

Production values are so-so at best with an unusually loud music soundtrack obliterating much of the dialogue. In this high school, no one ever goes to class, the kids are too old and Efron is too short for a basketball star but otherwise,"17 Again" is the epitome of realism.

Opens: April 17 (Warner Bros.)
Production: New line Cinema presents an Offspring Entertainment production
Cast: Zac Efron, Leslie Mann, Thomas Lennon, Michelle Trachtenberg, Sterling Knight, Melora Harin, Matthew Perry
Director: Burr Steers
Screenwriter: Jason Filardi
Producers: Adam Shankman, Jennifer Gibgot
Executive producers: Toby Emmerich, Mark Kaufman, Keith Goldberg, Jason Barrett
Director of photography: Tim Suhrstedt
Production designer: Garreth Stover
Music: Rolfe Kent
Costume designer: Pamela Withers Chilton
Editor: Padraic McKinley
Rated PG-13, 100 minutes