Cartoon Brew noted this earlier, but Keith Lango is continuing an excellent series of blog entries where he takes sample stills from recent animated features and discusses where they succeed and where they fail. His focus is on colour and composition and he argues that the nature of cgi production pipelines are working against the creation of good imagery.
All the articles are still on his main page. Start with the entry for October 29 and read forward. Keith isn't done with this yet, but it's already a must-read for those working in animation and anybody else trying to get a better appreciation for how images are put together.