Middle of the pack Pixar fare. Better than Monsters Inc. and Cars, but behind Nemo and Toy Story 2. [Bug's Life is still my all-time Pixar favorite].
Ratatouille had a cute storyline and impressive CGI, but it was not particularly funny. One other gripe: Having once had the onerous (and horrifying) task of deratting our cramped under-the-house crawlspace, I don't find rats cute and endearing.