Dennis Muren, I understand, did some special effects during the live-action sequences, so I'm guessing that those sequences were milestones in technological innovation.
But I haven't seen the movie. The only Pixar movies I like are Toy Story 1 & 2 and The Incredibles. And The Incredibles would have been infinitely better as a live-action movie.
To be honest, if Wall-E was 100 percent live-action (with special effects, of course), that would boost my chances of seeing it in the theater.