Starring Zach Braff, Amanda Peet, and Jason Bateman. Rated PG.

I'm not sure when, let alone why, Zach Braff got appointed the official stand-in for young American everyguys, but a class-action suit shouldn't be out of the question. Personally, I enjoy the Scrubs star's laid-back charm, essentially that of a younger Ray Romano with less chin but sexier mates. (For you kids in the crowd, he's like a more uptight, older Justin Long.)

Whoever he reminds one of, Braff has a curiously passive demeanour for a leading man. In The Last Kiss and his own Garden State , we're asked to sympathize with his existential paralysis, and we do, but not quite to the point of admiration. In The Ex , he plays Tom Reilly, yet another would-be winner stuck on the replay button of life. Tom is married to Sofia (Amanda Peet), a hot lawyer (in both senses) about to give up her practice to become a full-time mother and rely on hubby's income as a struggling chef.

On the eve of fatherhood, Tom loses his temper and his job, so the couple decides to downsize in small-town Ohio, where her parents live. Fortunately for us, those folks are played by Mia Farrow–who, like Peet, isn't given quite enough to do–and Charles Grodin, the authoritatively funny voice of the quietly desperate WASP. Dad works at an offbeat ad agency (in small-town Ohio?) and is able to take Tom on and put him under the tutelage of hotshot Chip Sanders, played unforgettably by Jason Bateman, who easily steals the movie. Despite his creativity, intense managerial skills, ability to get things done, and confinement to a wheelchair, Chip is one grade-A asshole.

Tom rankles at the situation from day one, but when he discovers that Sofia and Chip were lovers in high school–well, the whole thing rocks his world, and not in a good way.

The movie is directed in an amiable if sometimes too leisurely fashion by Jesse Peretz from a script by David Guion and Michael Handelman that gets funnier as it moves along. (The writing duo is working on the next Sacha Baron Cohen movie.) Tonally, the thing wavers between the in-your-face trangressions of Peter and Bobby Farrelly and the more character-driven comedy of Judd Apatow (of The 40 Year Old Virgin and Knocked Up ) without truly finding its own feet.

Like Tom, the movie is at its best when most fearless. Somewhat disappointingly, then, it pulls back from the toughest stuff by changing the central premise right at the end. The Ex is likable enough, but it could use a little more chin.