Following two horrific live-action versions of Theodore "Dr. Seuss" Geisel's beloved children's stories, the author's estate wisely decided to keep the next Seuss-to-screen translation in the animated realm. But even though the new cartoon Horton Hears a Who! comes closer to capturing that elusive Seussian magic than any adaptation since Chuck Jones' seminal 1966 short How the Grinch Stole Christmas, it also illustrates the inherent difficulties of blowing up one of the good doctor's books to feature length. To paraphrase Horton's own personal philosophy, sometimes a good story's a good story, no matter how short.

At least screenwriters Cinco Paul and Ken Daurio remain faithful to the broad outline of Seuss' narrative, even quoting the book directly at times in voiceover narration. Like the book, the movie begins on the 15th of May, in the jungle of Nool, in the heat of the day, in the cool of the pool. That's where Horton the Elephant (voiced by Jim Carrey) is relaxing when he hears a small noise emanating from a speck of dust that floats past him on the warm breeze. He soon discovers that the speck is home to an entire city of Whos, known appropriately enough as Who-ville. Horton makes contact with the town's mayor (Steve Carell), who requests his help in locating a safe place for their speck to settle. Of course, none of the elephant's friends believe his crazy story and one Nool resident, Kangaroo (Carol Burnett), even considers Horton's beliefs to be a menace to their community. So she enlists local bird of prey Vlad (Will Arnett) to swipe the speck away from Horton and prove her point that if you can't see or hear something, it doesn't exist.

Visually, Horton Hears a Who! is a delight; rather than follow the current trend towards photorealism in 3D animation, the folks at Blue Sky Studios (the company behind the Ice Age franchise) use Seuss' distinctive artwork as a jumping-off point to create their own colorful cartoon universe. The backgrounds are bright and beautiful, the characters are creatively designed (Horton's giant ears, for example, have been given a personality all their own) and the action/chase sequences are as fluid as anything Pixar has put out there. But the film's pièce de résistance is Who-ville, a marvelously imagined metropolis that resembles nothing less than a giant Erector set as designed by M.C. Escher. Buildings lean at perilously odd angles, staircases twist around on themselves and human...uh, make that Who-sized slingshots double as elevators. While motion-capture epics like Robert Zemeckis' underrated Beowulf and James Cameron's upcoming Avatar hint at a spectacular future for animation, it's still a pleasure to see a cartoon that so thoroughly enjoys being a cartoon.

Unfortunately, the filmmakers aren't able to crack the problem that also stymied Ron Howard and Bo Welch, namely finding a way to tell a story in 90 minutes that Seuss told brilliantly in 60 to 70 pages. On the page, Horton Hears a Who! is a simple, straightforward argument against prejudice, intolerance and groupthink. The film hits all of the same beats, but pads them out with invented subplots and comic asides. Some of this new material plays quite well, including a hilarious fantasy sequence where Horton imagines himself the hero of a pitch-perfect Pokémon parody. (The animators even remember to include the onscreen onomatopoeia and pulsating hypercolor backgrounds that are staples of anime.) Considerably less effective, though, are storylines involving the Mayor's family life, most notably his attempts to bond with his son JoJo (teen pop idol Jesse McCartney—no relation to Paul), who is nursing some boring adolescent angst that his dad understandably doesn't seem to care about. These scenes add little to the larger narrative arc and, even worse, traffic in the kinds of clichés that Seuss himself managed to avoid.

Horton's vocal performances are uneven as well; while the supporting players vanish into their roles (although Burnett's voice is instantly recognizable), Carell and Carrey make the mistake of forcing their characters to conform to their own established comic personalities. Hence, the Mayor all too often sounds like Michael Scott (Carell's character on the NBC sitcom “The Office”), while Horton comes across like...well, like an animated Jim Carrey, with lots of pop-culture quips and celebrity impersonations always at his disposal. Someone should have explained to him that Horton's appeal doesn't lie in his ability to mimic Tony Montana, but in his self-confidence and steadfast commitment to doing what's right. While Horton Hears a Who! won't enrage Seuss' legions of fans the way The Cat in the Hat and The Grinch did, it only scratches the surface of what makes the author's works resonate.