It's been five years since Ivan Reitman's Evolution, almost a generation in the film industry. In fact, most of the potential audience for My Super Ex-Girlfriend wasn't even alive when Reitman helped rewrite the rules for movie comedies back in the 1980s. The director reworks ideas from his biggest successes in his new project, giving My Super Ex-Girlfriend the feel of a greatest-hits package at times. But despite clever writing by "Simpsons" veteran Don Payne, this high-concept comedy lacks the star power to become a true blockbuster.

The opening is quick and efficient, with nerdy architect Matt Saunders (Luke Wilson) winning art gallery manager Jenny Johnson (Uma Thurman) by trying to catch a purse-snatcher. Their first tentative dates reveal Jenny to be neurotically grasping and Matt next-to-spineless. It turns out that Jenny is also G-Girl, a superheroine whose exploits are often just another inconvenience for jaded New Yorkers.

Jenny makes Matt promise not to reveal her secret identity, even when her archenemy Professor Bedlam (Eddie Izzard) hangs him from the torch on the Statue of Liberty. But Matt soon learns that his biggest problem is Jenny's superhuman neediness. When she discovers that he's falling for his co-worker Hannah Lewis (Anna Faris), G-Girl responds by hurling his car into orbit.

The rest of the film details Matt's attempts to placate Jenny and declare his love for Hannah, just like Robert Redford playing off Debra Winger and Darryl Hannah in Legal Eagles. In the meantime Bedlam concocts a scheme to destroy G-Girl once and for all, a plot device that can't disguise the fact that My Super Ex-Girlfriend is all setup and no payoff. Reitman flirts with some off-color material, throws in one special-effects sequence involving a shark that evokes the euphoric action in Ghostbusters, and then basically treads water until the contrived happy ending.

Thurman doesn't hold back, either as Jenny or G-Girl, injecting a sexy energy into a film that can sometimes seem stodgy. Supporting players like Izzard and Rainn Wilson (from NBC's "The Office") make the most of their underwritten parts. Izzard's explanation of the difference between "kill" and "neutralize" is a textbook example of shaping material to fit a personal style. But Luke Wilson, whose changing hair color suggests that the film underwent a lot of reshoots, proves that in a project like this, being affable isn't enough. He and Faris, a fixture in the Scary Movie franchise, can't generate enough excitement to keep the film afloat. Their romance, the least interesting aspect of the story, is more insipid than wholesome.

The real question My Super Ex-Girlfriend poses is how much of an audience remains for Reitman's glossy, brand-name style of comedy. The funniest parts of the script, like its characters' casual acceptance of a comic-book reality, are so subdued that they can be missed entirely. Reitman plays up the story's sex, but seems reluctant to go as far as The Wedding Crashers or The 40 Year Old Virgin. With special effects and action that seem a bit too casual, My Super Ex-Girlfriend will have trouble competing against the summer's juggernauts.

-Daniel Eagan