There are two main reasons why I enjoyed Ratatouille more than any other animated film that I've seen in the past...oh, let's say twenty years? That seems about right.
1) I love Patton Oswalt, and even though he did not write the movie, it's sort of amazing how much it seems as though the project was created as a way of bringing his aesthetic to the masses. When I say that, I don't mean his shtick. What I mean is, the film is dealing with the central motif of his body of work: the dilemma of being a tasteful, thoughtful person trapped in a world full of unthinking bores. I know that sounds incredibly snobby, and sometimes it is, but it's urgent and key, especially when ignorance and anti-intellectualism becomes a destructive force rather than just an aesthetic irritant. So there's that, and the fact that Oswalt happens to have a keen interest in fine dining, and the maybe-not-totally-coincidental casting of Brian Dennehy -- a man who has been invoked in at least two of his best bits -- as the father of his character.
2) As I said, Ratatouille is a movie about taste, but more than that, it's a general audiences picture that intelligently and sensitively explores the tension of art, criticism, and consumerism. Most animated features are either vehicles for dumbed-down jokes and/or cloying tearjerkers*, but Ratatouille is mainly concerned with making an argument that brilliant creativity can come from anyone, anywhere, even if it is met with resistance from indifferent philistines, crass consumerists, or overly mannered snobs. Of course, the latter is represented by a ridiculously self-important food critic voiced by Peter O'Toole, and though for most of the film he is portrayed as an insufferable prick just like pretty much every other fictional critic ever created, he eventually comes around to revising his opinions when confronted with a dish so sublime that he's overcome with a Proustian involuntary memory. The film's stance on criticism is a bit garbled -- predictably, criticism is connected only to negativity, and the appreciative, philosophical end of the discipline is represented mainly by its creative protagonist and the writings of a deceased chef who serves as his primary inspiration. However, even though I currently make my living as a critic, the part of me that went to art school can't help but agree with the film's basic point: We should all own our taste and develop our critical faculties, but we should use that as a starting point for our creativity rather than to let it fuel our ego and turn us into petulant, persnickety consumers.
* I don't want to totally knock the tearjerkers. Finding Nemo is a worthwhile film even if it's not totally my thing, and I'll level with you -- I was totally DESTROYED by An American Tail when I was a little kid, and I still get choked up if I hear "Somewhere Out There" on the radio.