A big-screen adaptation of the 2002 Tony-winning Broadway musical by Marc Shaiman and Scott Wittman (itself based on the 1988 John Waters cult classic), this third "Hairspray" incarnation is the weakest of the bunch but a lot of fun all the same. Directed and choreographed by Adam Shankman (2003's "Bringing Down the House"), the film is packed wall-to-wall with bouncy song-and-dance numbers and an eclectic ensemble of game actors relishing the chance to dig into their colorful roles. It's certainly a crowd-pleaser, but also so overstuffed with subplots and filler scenes where not much happens that it sometimes loses sight of what should be its focal point: pleasantly plump, irrepressibly free-spirited teenager Tracy Turnblad.

In the city of Baltimore, circa 1962, the hottest television program around is "The Corny Collins Show," a teenybopper dance-athon that 16-year-old Tracy (Nikki Blonsky) dreams of being a part of. When a space suddenly opens, Tracy takes a shot at the auditions and, much to the chagrin of bigoted show producer Velma Von Tussle (Michelle Pfeiffer) and stuck-up daughter/head dancer Amber (Brittany Snow), wins the spot. As her star rises and she inspires her hefty mom Edna (John Travolta) to leave the house for the first time in ten years, Tracy gets a bitter taste of the real world when the show demands the segregation of whites and blacks and, even worse, subsequently takes away Negro Day. Having befriended African-American classmate Seaweed (Elijah Kelley) and his mother Motormouth Maybelle (Queen Latifah), Tracy, school crush Link Larkin (Zac Efron), and best friend Penny Pingleton (Amanda Bynes) decide to take a stand against the establishment and prove to Baltimore that integration is the future of the country.

Less focused than John Waters' subversive and satirical original and unjustifiably lacking the highlight number from the Broadway show ("Mama, I'm a Big Girl Now"), "Hairspray" nonetheless brings a smile to your face and is destined to get your feet tapping. The musical set-pieces are fabulously shot and cohesively edited in a way that doesn't rely on flash cutting and unnecessary kineticism. By letting these scenes breathe and allowing the actors to live within their performances for longer than two-second shots at a time, the picture pleasingly resembles a musical one might have seen get made in the actual 1960s. This carries over to the production design, by David Gropman (2006's "Little Children"), with a less flattering outcome; the movie is aesthetically vibrant, but its soundstage-heavy portrayal of Baltimore in comparison to Waters' on-location shooting resembles a Disneyland version of the town and era.

Just about every musical interlude is catchy, but a few stand out above the rest. Tracy's opening number, "Good Morning, Baltimore," kicks the proceedings off with energetic aplomb, a winking sense of humor and a special cameo by John Waters playing "the flasher who lives next door." "The Nicest Kids in Town" is a peppy, superbly choreographed introduction to "The Corny Collins Show" that also sets up Tracy's desire to dance on the show and her affection for handsome Link Larkin (the latter directly sung about later in Tracy's sweet solo "I Can Hear the Bells"). "(You're) Timeless to Me" is a whimsical duet between married couple Edna and Wilbur (Christopher Walken) as they rekindle their romantic flame. "Without Love" is a delightful love ballad between couples Tracy and Link, and Penny and Seaweed. "I Know Where I've Been," brilliantly performed by Queen Latifah, brings down the house as Tracy and the black community courageously march through the streets of Baltimore. The climactic "You Can't Stop the Beat" invigoratingly brings the multiple story threads and characters to a close. Finally, the best number in the film is "Welcome to the Sixties," a purely magical song between Tracy and Edna as they step out on the town and Edna regains the self-esteem and joy long missing in her life.

The cast is mostly in uniformly fine shape, with newcomer Nikki Blonsky leading the way in a star-making turn. Blonsky is giddy, strong-willed and absolutely lovable as Tracy Turnblad, and a great singer, to boot. Right behind her is John Travolta (2007's "Wild Hogs"), a touching and funny scene-stealer as mom Edna. Travolta wisely does not camp up the role, but plays her as a real woman through and through. That Travolta is able to do this so believably behind the fat suit, latex and make-up is all the more commendable.

Amanda Bynes (2006's "She's the Man") essays the part of lollipop-sucking best friend Penny Pingleton with less dippiness and more unassuming sensuality than has been depicted in the past. Michelle Pfeiffer (2002's "White Oleander") is as despicable as despicable can be as the racist Velma Von Tussle, but she does it with enough comic flair that she never is unpleasant to watch. And Queen Latifah (2006's "Last Holiday") is wonderful and wise as Motormouth Maybelle. Less successful, although due more because of the writing than the acting, are Zac Efron (Disney Channel's "High School Musical"), a little too reliant on surface than subtext as Link Larkin; Brittany Snow (2006's "John Tucker Must Die"), boring as Tracy's main rival Amber Von Tussle; and Allison Janney (2006's "Strangers with Candy"), funny but largely wasted as Prudy Pingleton, Penny's religious zealot mother.

"Hairspray" covers some historically relevant topics, including the slowly evolving racial climate of the 1960s, but overall it is nothing more than a frothy, cotton-candy bit of entertainment. As such, its 107-minute running time is too long to withstand the material. Screenwriter Leslie Dixon (2005's "Just Like Heaven") and director Adam Shankman should have reevaluated what was and wasn't important, and could have improved the uneven pacing by cutting some of the more extraneous scenes—the business between Velma and Wilbur at the magic shop comes instantly to mind. The music, while memorable, also gets to be too much in the second half, with a couple needless numbers pulling the central storyline and protagonist Tracy out of their deserved limelight. "Hairspray" is far from seamless in its journey from stage to screen, but it is buoyant and sunny and likable despite its problems. Expect at least a couple of the songs to get stuck in your head for days after.