We saw it yesterday afternoon. My DW thought it was better than The Incredibles (but she admitted that she doesn't really like violence). She prefers the Toy Story movies and Monster's Inc.
I thougt it was excellent, although I preferred The Incredibles (see, I do enjoy violence, especially when done by superheroes, but that's me). The attention to details is astounding. About half way through, I agreed with the critics who complained that there's nothing intrinsically warm or fuzzy about cars, but I noticed that I was hooked by the final race, actually rooting for Lightning.
DD6 says she loved it. However, like so many other posters said, her interest flagged in the middle. I don't think it's a movie for really young kids, who might find it a bit plot heavy.
But, man, is it beautiful.