I just saw Blue Sky's Horton Hears a Who, and it was absolutely incredible. By far the best movie I've seen in theaters over the past couple years.
It's the CARTOONiest 3D movie I've ever seen, and I think Blue Sky is going to carve out a real niche for themselves in the market with this kind of stuff. It was pretty funny and had a lot of great 2D oriented gags which was awesome to see in 3D. There is also about 3-4 minutes of 2D animation in the film which was a great surprise, and they made it work. Originally I wasn't too keen on the voice cast, but as the movie progressed they actually fell into place really nicely.
Taking a kids book like that and adapting it into an hour plus film will surely have its difficulties, and it showed. There was some filler bits, but I think they kept a great flow to the movie that was entertaining enough to distract from the fact. I think one of the reasons it succeeded was because it treated its filler sequences as animated shorts; the whole bridge scene for example, could stand alone as a short (if you remove the spec from the scene). A giant elephant who has to cross a thin decaying old rope bridge. That's a great gag short. They did not fill the extra time with irrelevant dialogue or scenes in which they establish characters/relationships that ultimately have no significance in the movie's entirety.
Does anybody else smell a sequal...