Saw a presentation at SIGGRAPH this year by these guys, talking about this exact thing. They spent a ton of time and effort making sure to stay true to the source material - both the comics and the old animations. They had to create multiple models for the main characters, since they don't translate to 3D well, and just switch between them quickly when your view of them changes. The presentation had some great shots of showing the 3D models from angles you're never meant to see them at, and seeing how messed up they are. Snoopy basically looked like a Picasso.