I like Cars because up until 1.5 years ago, my grandparents lived in a place that might as well have been called Radiator Springs. So it hit home in a rather personal way, which forced a different sort of response than Pixar films tended to do (until Wall-E and Up, respectively). I think it looks nice and has enough amusing parts to put it firmly in the "ok" category, and easily better than most films from other studios, animation or not.
Besides, I give them props for fleshing out the world in a fairly believable way. I.e., look at Madagascar. It's like they gave up halfway through designing the main characters ("wacky" mane on the lion sliding into fairly generic animal models). Cars, though, has a lot of nice touches to further inject its overall motif into - the "cow" tractors are the most immediate example. Pixar stuck to this design work and it works throughout the entire framework of the movie, where as most other studios would crap out and not care.
Just seems like the movie as a whole garners a lot more hate than I think is warranted, and I'm guessing a lot of that comes solely from The Cable Guy being a voice, despite that he did a competent job, and Pixar - knowing he'd be popular - decided to base most of the advertising around him. Which is a shame, because there's more meaning to the movie than that.
(Note: Madagascar sucks by the way.)
Bug's Life is the worst Pixar movie. No contest. I put Toy Story 2 in the lower echelon as well, hence why I'm still concerned on this new one.
Finally, a note about Ratatouille: the human sections are some of the best things Pixar has ever done. Linguini is perfectly acted and animated, as well as Skinner (the short head chef). You can't tell me those guys are hilarious to watch every time. Meanwhile, I can't

ing stand the shit with the rat family, ESPECIALLY the ending. It makes me want to puke. Same with the "dog"fighting in Up. Yeah, that's kind of a clever thing, but Pixar relies far too heavily on "wacky band of characters doing wacky things." Hell, even Wall-E breaks into that, and it's just a cheap palette switch for Toy Story. They've shown they can be leagues ahead of that trick, and they really should keep that up.
Still, hope to see TS3 soon. Positive reviews on here give me more hope.