Female 'Big' a little wobbly

After the success of "Freaky Friday" last year, it's not surprising that "13 Going on 30" is opening with a big publicity splash. Moviegoers are eager to explore the hazy dividing line between adolescence and adulthood - or so Hollywood thinks, at any rate.

You won't find a load of laughs in "13 Going on 30," but there's plenty of whimsy, which is a close cousin of genuine humor. And there's lots of old-fashioned romance, always a box-office plus even when it's as sugary as it is here.

Jennifer Garner plays Jenna, a girl who'd rather be cool, like the hip teens she envies, than unconventional, like the next-door neighbor she spurns. Determined to win her, the neighbor builds her a dollhouse for her 13th birthday, throwing in a packet of "wishing dust" as well. The dust does its stuff when she yearningly wishes she were "30, flirty, and thriving," a slogan she's seen in a fashion magazine.

The screen goes blurry, and suddenly she's all of the above - and also mighty confused, since she has no memory of growing up. But she soon gets the hang of her adult job, which is editing the magazine that inspired her as a kid. Her chief nemesis works there too, scheming against her down the hall.

Jenna also looks up the boy she treated so badly years ago. She really likes him now, but wouldn't you know, he's getting married in two weeks. Will she be stuck with the dopey boyfriend she acquired during her "missing" years? Is 30 less fun than it's cracked up to be?

Garner gives her all, which isn't enough to salvage the movie's early scenes, full of too-familiar situations and stereotypes. She and the story pick up steam, though, when Jenna settles into her 30-ness and takes on a crisis at her magazine. And it's hard to resist the scenes with Mark Ruffalo as the grown-up version of her adolescent suitor. His gentle, laid-back manner is just what the picture needs to keep a reasonable degree of plausibility and charm.

"13 Going on 30" is no competitor for "Big," still the classic in this genre. Yet while Garner is no Tom Hanks, she's consistently appealing, and that should help this comedy-fantasy thrive.

• Rated PG-13; contains sexual references.