You really are complaining about his quills.
Fine, here's one thing to chew on: we've established Sonic 4's Sonic is polygonal, not 2D artwork. So they can't just draw a mess of yellow pixels with a couple points of different thickness sticking out, it has to be something that works on a polygonal model, and can be seen from more angles than his left side and right side and still work.
A fairer comparison would be Sonic 3, which at least started from a 3D model render, although they still did touch-up on the output I'm sure:
The big difference is that he doesn't have an obvious quill sticking out from his back, and the length's a little more balanced out, but I don't see a big issue personally.
Of course, invariably now we disown Sonic 3's art, etc, etc. So I'm not going to take this any farther. But I really thought your "so much more" was going to be about a mode or moves or level or something, not a thinly-veiled repetition of the same physics complaints and "his quills are amateur!" :lol