If Pixar is the gold standard for modern computer animation, Blue Sky Studios rates a metallic silver for Robots, the visually overwhelming followup to their wintry feature debut, Ice Age. Lacking the charm and narrative drive of a Finding Nemo or Incredibles, director Chris Wedge's sophomore outing is nonetheless a spectacular achievement, conjuring up an entire imaginary world that's unlike anything seen onscreen before.

Playwright David Lindsay-Abaire and comedy veterans Lowell Ganz and Babaloo Mandel assembled the screenplay about a society entirely comprised of mechanical beings, where even the lamppost, the mailbox and the fire hydrant are liable to express an opinion. Our hero is Rodney Copperbottom, an idealistic inventor from the working class (his dad is a dishwasher, literally), who leaves his modest home in Rivet Town to try to make his fortune in big and bustling Robot City. But Rodney's idol, celebrity entrepreneur Bigweld, is nowhere to be found; he's been usurped by scheming exec Ratchet, who's changed the company philosophy from "You can shine no matter what you're made of" to "Why be you when you can be new?" in a cruel campaign to eliminate replacement parts and dispose of outmoded robots who can't afford upgrades.

Spurned by Ratchet, Rodney ends up on the poor side of town, where he does a brisk business rejuvenating broken-down members of the community. (All that's missing is his own reality-TV makeover show.) Word of Rodney's brilliant repair talents spreads all the way to the upper echelons of Bigweld Industries, and he soon finds himself leading a grass-roots (or perhaps nuts-and-bolts) revolt against the corporation's nefarious extinction program.

It's curious that this tale of a (cyber) people's revolution comes from Rupert Murdoch's conservative media empire, but then again, so does "The Simpsons." Trouble is, the message isn't as subtly integrated into the story as in the brilliant Pixar scripts, giving a somewhat leaden (pun intended) quality to the narrative. The movie really doesn't perk up until Rodney is befriended by a corroded bunch of misfits dubbed "The Rusties." Best of that bunch is the invaluable Jennifer Coolidge as the voice of Aunt Fanny, a motherly robot with a rump that's far too big for her tiny home. (Teen favorite Amanda Bynes also turns in a spirited performance as Piper Pinwheeler, a tomboy with showerhead-shaped pigtails.)

Though it takes a while to find its (ball) bearings, Robots is a consistently inventive visual experience. The public-transit system that Rodney encounters on his arrival in Robot City is a dementedly vertiginous, Rube Goldberg-like thrill-park ride, and the production design is crammed with clever, blink-and-you-missed-it gags (like the plug and outlet symbols on the public restroom doors). The CGI designers create a wonderfully realistic look for the characters, all distressed metal, rust, and other signs of wear and tear, while bringing lots of imagination to their zany assembly of spare parts. The movie also ends excitingly, with a massive battle out of a Hong Kong action epic, and a delightful musical number that out-Shreks Shrek.

The wide-ranging voice cast is uniformly good; even that showoff Robin Williams manages to stay in character most of the time as a frantic con artist named Fender. Ewan McGregor maintains a disarming innocence for Rodney; Halle Berry exudes warmth and sexiness even in her shiny guise as a corporate robot who falls for the young inventor; Greg Kinnear makes an energetically hissable villain as Ratchet; and Mel Brooks lends his inimitable presence to robot legend Bigweld. The wildest casting choice is Jim Broadbent as the voice of Ratchet's evil, tyrannical mother, who runs the city's dreaded Chop Shop. Most unrecognizable is Sideways' Paul Giamatti as the giddy little guy who guards the entrance to Bigweld Industries, one of several references to arguably the greatest family movie of all, The Wizard of Oz.