Chewie's look suffered the same fate everything else in the prequels has - it looks too "new" and clean, so to speak. Same thing happened with Yoda. Regardless if it's TPM, AotC or RotS version, none of them look like the cool puppet from ESB, but it's still Yoda.
Personally I'm a big Chewie fan, but he wasn't in the film enough to really warrant being included. They should've just used some generic Wookie instead.