The setup is cute stuff as Jenna Rink (played winningly at age 13 by newcomer and Garner look-alike Christa B. Allen) prepares for her birthday party in 1987. Envious of a conceited squad of popular classmates, Jenna strives to be part of the elite clique, but winds up spending most of her time with Matt (Jack Salvatore, Jr.), her devoted admirer from next door. After a traumatic party experience in which she's betrayed by the clique, Jenna winds up in the closet wishing to be 30, spurning the lovesick Matt and rocking off to sleep.
She awakens as a startled adult with a naked hockey-star boyfriend in hot pursuit. Events lead Jenna to the location of her dream job--editor of the fashion magazine she read when she was a kid. Her boss (Gollum himself, Andy Serkis) interprets Jenna's confusion and youthful attitude as a refreshing new spunkiness, and her confounded best friend and co-worker Lucy (the very funny Judy Greer) wonders what happened to her backstabbing, career-focused compatriot.
Like Hanks in Big, Jenna thrives at her adult job despite the skipping of many years of experience. Instead of dancing "Chopsticks" on a toy piano in a Manhattan toy store, Jenna leads lethargic partygoers in a Thriller dance-along that saves the day. (The scene isn't as ghastly as it sounds.)
While all of the occupational humor is amusing, the true heart of the film lies in Jenna's relationship with the adult Matt (Mark Ruffalo). After seeking him out and discovering that her 13th birthday party was basically the last time they talked, Jenna does her best to make amends and heal the friendship. Garner and Ruffalo play this portion of the film to sweet rewards. The two have nice screen chemistry.
Will Jenna stay a 30-year-old woman and woo the adult Matt away from his snotty fiancée? Will her school-yearbook editing tactics catch on at her magazine, insulting all who have received their master's degrees and endured countless episodes of backbiting and bending over to reach meager heights in the editorial world? It's safe to say that many will find the film's wrap-up safe, yet undeniably adorable.
The offbeat casting of indie favorite Ruffalo lends a nice level of credibility to the proceedings. While he's perhaps been better in more serious pictures (You Can Count on Me, for example), he's never been this likeable in a film. As the grown-up Matt, he does a nice job of conveying the joy and confusion of a man who gets a second chance with the first love of his life.
As charming as Ruffalo is, the film does belong to Garner, who instills the age-old body-switching movie gimmick with a newfound energy. This is a role that could've easily been overplayed, but Garner finds the perfect balance of sentimentality and slapstick to make Jenna's impossible fate tangible in the fantasy movie world.
After a stretch of admittedly good but ultra-violent and generally unpleasant fare such as The Passion of the Christ and Dawn of the Dead, 13 Going on 30 amounts to sweet relief for punch-drunk moviegoers. It induces many a smile, perhaps a tear or two, and succeeds in not letting a single character graphically bleed to death during its running time.