Fans of the TV series Alias will know that part of what makes Jennifer Garner's Sydney Bristow such an excellent secret agent is her ability to commit herself fully to her undercover identities, developing a different personality for each new role. Fans will also recognize that Garner's own remarkable acting skills are what make the character work: Not only does she nail each undercover identity, but she also lets Bristow's personality shine through all the put-on personas. Though the film gives her ass-stomping abilities a rest, those Alias skills make Garner uniquely suited to star in 13 Going On 30, in which she plays a 13-year-old who magically wakes up in the body of her 30-year-old self, as if she'd skipped the years between 1987 and 2004. She's convincing as a teenager in a grown-up body, but she's also convincing as a teenager in a grown-up body trying her best to act unfazed by the adult world.
So cheers and many happy returns to Garner as she makes her first starring film role. She's the real deal. But jeers to every other aspect of 13 Going On 30, which plays like a long-unproduced screenplay from the late-'80s glut of body-swapping comedies that brought the world Like Father, Like Son and Vice Versa. After heavy foreshadowing, a "wish dust"-aided Garner wakes up as the high-powered editor of a New York fashion magazine. After getting over the shock of finding a naked man in her apartment—to which she responds with the oft-repeated exclamation "Oh, gross!"—Garner quickly discovers that getting everything she wanted at 13 has its downside. She's lost touch with a best friend who grew up to be Mark Ruffalo, for one thing. For another, she seems to have turned into an unrepentant shrew, ignoring calls from her parents, sleeping with married men, and generally behaving badly.
Apart from the moment when Garner unselfconsciously flirts with a 13-year-old boy, the film is pretty much devoid of comic spark, and though it seems to have sweet intentions, it keeps sending mixed messages. It opens by portraying the 13-year-old Garner's life as a string of horrors, but then has her character spend most of the film trying to convince everyone about the magic of teendom. There's also a none-too-subtle suggestion that only awful women get ahead in business, and that they live miserably once they do. If Garner's character were paying attention, she'd sink into depression at the thought of being either age, but then the movie probably couldn't easily end with an uptempo Pat Benatar song.