In Rock of Ages, a new star-clogged pop-musical diversion based on a "jukebox musical" where a story is built around an afternoon of VH1 Classics' worth of 1980s hair metal, Tom Cruise has the advantage of playing one of those built-up parts, like Harry Lime, or Hickey in The Iceman Cometh. Everyone in the first act talks up "Stacee Jaxx," so he can't help but be impressive by the time he shows up — a fine fit for a star who by now can only really be convincing as a star. Cruise is a dynamic, kabuki-esque, full-body performer, and he gives Jaxx something between the boozy silverback swagger of Jim Morrison and Glenn Danzig's armored-car presence. The original author of the West End stage show, Chris D'Arienzo, is joined for the screenplay by Justin Theroux and Allan Loeb, and they have drafted something that combines elements of Menahem Golan's The Apple, Empire Records, the Guns N' Roses video for "Welcome to the Jungle," and Tipper Gore's '80s career as PMRC scold. Choreographer-cum-director Adam Shankman (Hairspray) keeps things assaultively lively, hot-potatoing songs around the cast — including Julianne Hough, Catherine Zeta-Jones, Russell Brand, Paul Giamatti, and Malin Akerman — and crosscutting in Frankensteined mash-ups. A key plot point depends on the belief that there's more artistic integrity in being a member of, say, Poison, than in being in New Kids on the Block, as if hair metal were not bone stupid, creatively bankrupt, morally debased pop trash that marked an all-time low in record-label-chart manipulation and synthetic hit-making hackery.