This is the funniest movie I've seen in years, and probably one of the funniest movies I've ever seen. In terms of sheer jokes-per-second, this film is unmatched. During nearly EVERY SINGLE SCENE for the ENTIRE RUNNING LENGTH, there is always a joke hidden somewhere, either in the background or in the main action (or both). And the jokes are at the epitome of timing and delivery, being absolutely silly and genius at the same time. No movie I've seen has ever come close to matching the number of laugh-out-loud moments found here.
Then, you've got the damn-near perfect art direction, hilarious animation and characters, unique and gripping story, wonderful pacing and well-chosen, pertinent, better-than-usual morals. All of this combines to make something I thought was impossible: a CG animation movie that rivals Pixar's work. Of course, that's more in a "what the hell was in this brownie I just ate" way than in a "wow that's so touching and thoughtful!" way.
In a sentence:
Unforgivingly hilarious, perfectly executed, full of heart, and 3D. The most fun you will have in the movie theatre in the last few years.