(CNN) -- Tom Cruise should have been a rock star.
Remember him pounding his air guitar in not much more than a shirt and shades in "Risky Business"? He turned a pool hall into a concert stage, strutting his stuff in "The Color of Money," shook his moneymaker under layers of latex at the end of "Tropic Thunder" and took a chance, singing in his own voice in "Top Gun" and "Magnolia." He always had the moves, and more important, he had the self-belief. He turns himself on.
Still, the challenge of a full-blown musical has apparently not been something he's been in a hurry to tackle, perhaps wary of undercutting his action-man credentials. Turns out, some things are worth waiting for.
I don't know how much they may have finessed his vocal tracks, and it doesn't matter. He owns "Rock of Ages," an addled tribute to '80s hair metal, from the very minute he appears. He emerges hazily from underneath layers of discarded groupies in a palatial hotel suite, sporting gunslinger body art and outrageous crotch jewelry, dispensing intensely eccentric, deeply fried philosophical nuggets before stumbling into the indoor Jacuzzi. Ladies and gents, meet Stacee Jaxx, God of Rock.
A caricature of already larger-than-life personalities Axl Rose and Steven Tyler, Stacee is very much a supporting character in Chris D'Arienzo's Tony-award-winning 2009 musical. But he's also the star of the show, the one everybody else is dying to see, to make or to emulate. Cruise has the charisma to sell all that even as he shows us a boozed-up captive to celebrity, sex and ego. When he does perform, he's electric. However, Cruise is just as good in the dialogue scenes, whether it's messing with club owner Alec Baldwin's vulnerable brain or fending off an increasingly hot-under-the-collar "Rolling Stone" features writer (Malin Akerman).
A karaoke musical in which almost everybody bursts into FM anthems at the drop of a hat (yes, even Baldwin, who duets with Russell Brand on a camp rendition of REO Speedwagon's "Can't Fight This Feeling"), by rights "Rock of Ages" shouldn't come off as a one-man show. But it's an uneven fight, and you might find yourself itching for the fast-forward button whenever Cruise is off-screen.
Julianne Hough, who portrayed Ariel in "Footloose" and who appeared in the strikingly similar "Burlesque," plays the movie's ostensible heroine, Sherrie Christian, a small-town girl from Oklahoma who gets off the bus in Hollywood ready to pursue her dream of being a singer.
Instead, she finds herself playing out a PG-13 version of "Showgirls," waiting tables at the legendary rock club the Bourbon Room and falling in love with a co-worker, Drew (Diego Boneta). Drew's own singing aspirations get considerably more screen time than Sherrie's, but he still fails to make much impact. Hilariously, within hours of meeting her, he claims to have been inspired to write "Don't Stop Believin." "It goes on and on," he explains modestly after giving her a taste of the first verse.
You couldn't accuse the filmmakers of taking themselves -- or anything else -- too seriously. Director Adam Shankman, the veteran choreographer who also directed "Hairspray" (and a couple of episodes of "Glee"), encourages the cast to amp everything up to 11, or in the case of Catherine Zeta-Jones, 111. She plays the mayor's wife, Patricia Whitmore, crusading to clean up the Strip and shut down the Bourbon Room for reasons more personal than political.
All this sound and fury signifies next to nothing, and music fans may feel it's a funny sort of tribute that mocks as much as it rocks. Even so, it's good to see Tom Cruise letting his hair down. It's a fun show if you roll with it.