Pixar took a lot of risks with this movie, for numerous reasons:
1) There's very little dialogue.
2) There's mixing of computer animation and live action.
3) It's relatively (and unexpectedly) dark with a high level of social commentary.
4) The story is primarily a love drama with some physical comedy thrown in.
And I have to say, they pulled each and every one of them off with flying colors. The small amount of talking works very well, and you get used to it immediately. It apparently did it well enough that it didn't even bore the smaller children that were in my theater, because I never heard a peep from any of them. The mixing of animation and live action, though it's not extensive, worked well. The last time I saw this was with Happy Feet, and it felt incredibly out of place. Here, it works very well and is almost seamless. The social commentary is very in-your-face, but I love movies with social commentary, so it was just another layer of awesome for me. Finally, the movie had the perfect amount of physical comedy to fit the tone of the movie. It wasn't overdone at all. And the romance built up gradually, as the relatively uncaring Eve slowly begins to care for WALL*E. It was cute, funny, and warming.
The animation of the movie is amazing. It was simply stunning, really (well, the humans were average, but everything else was stunning). From the moment the movie opens up on the city made of compact garbage, placed against a desert landscape, I knew I was in for a visual treat. And simultaneously, as the view is on this, the music playing over it is so haunting. The soundtrack to the movie was almost as brilliant as the animation. It could go from haunting to whimsical to musical-soundtrack and back again, and it was just wonderful.
I cared for all the characters, including the more secondary ones like the cockroach and M-O. I also loved how, from the moment WALL*E gets onto the AXIOM space colony, every accidental thing he does ends up having some kind of huge impact. If the movie could have done anything better, I think it could have played up that aspect a bit more.
But otherwise, I think this movie is almost perfect. I tried to think, on my 20 minute drive home from the movie theater, of something negative to say about this movie... and I honestly could not. I think this movie will deserve the Oscar it will inevitably win.