Rock of Ages is nothing but a good time and sometimes less, slogging through the knee-deep hoopla of 1980s nostalgia at a jukebox pace. The stage version is remarkably thin beyond its retro-hit songs; the movie adaptation magnifies that fault. Bang your head one minute, and shake it in bewilderment the next.It's the patchwork story of a small-town girl named Sherrie Christian (Julianne Hough) and city boy Drew Boley (Diego Boneta) falling in love and trying to make it big on L.A.'s Sunset Strip in 1987. There are the usual temptations, misunderstandings, rifts and mends for such show biz circumstances, with party anthems and power ballads interrupting their romantic chemistry.Hough made a nice impression in last year's Footloose remake, so her ordinariness here is chalked up as another of the screenplay's underwritten characters. Boneta has more going against him, a softness of spirit that would get Drew eaten alive in L.A. He can sing I Wanna Rock but isn't convincing about it. Boneta appears more at ease during Drew's silly boy-band phase than striking guitar-god poses.For that, Rock of Ages needs only Tom Cruise, sexy and startling as rock icon Stacee Jaxx, an expanded role in the movie version. His entrance is a model of celebrity decadence, slowly revealed post-orgy from beneath a blanket of obviously satisfied women. Stacee is the poster boy for sex, drugs (Scotch, at least) and rock 'n' roll, who could use sensitivity training from Axl Rose.Cruise plays Stacee in a style noticeably close to his turn as Lestat in Interview With the Vampire (who coincidentally wanted to be a rock star). There's a sad blankness in his eyes, too many wild nights and empty mornings. Yet when the topic turns to his music, and later his insecurities, Stacee's gaze seems possessed. Cruise's performance eclipses everything else in Rock of Ages; plus the dude can flat-out sing.Stacee's backstage orbit is where Rock of Ages finds its best material and cleverest shoe-horning of songs. He's the main attraction in concert at the Bourbon Room, run by seedy Dennis Dupree (Alec Baldwin) and his frisky flunky Lonny (Russell Brand). Their relationship takes a cheeky turn with the song I Can't Fight This Feeling, one of the rare times when director Adam Shankman hits his Hairspray stride.An interview with a Rolling Stone reporter (Malin Akerman) leads Stacee to confess I Want to Know What Love Is, matching the words with dirty deeds that never occurred to me when the song was on the radio. Stacee's immorality becomes the political target of the mayor's wife (Catherine Zeta-Jones), who wants the Bourbon Room closed, resulting in a seamless mashup of We Built This City and We're Not Gonna Take It. Such inspired sequences make Rock of Ages fun, but this rose has more than its share of thorns.Steve Persall can be reached at [email protected] or (727) 893-8365.