I also personally love how this 3-D modeled amazingly graphiced video was bashed for just being the game we've already played, yet no one has a problem for Sonic 2 HD.
Ah, that makes sense. Thanks.
This is an easy example. Normally you simply jump to get to the other sand slide. In 3D, that's not exactly possible. You're forced to slide on a straight path, and there's another slide next to you. If you jump, you either stay on your own slide, or magically warp to the other slide.
Didn't Sonic Rush basically make the character look like it changed planes? (As appearing gigantic or small)