I don't have too many issues with the amount of characters in the Sonic universe to begin with, though I still await the return of Fang the Sniper (or Nack the Weasel, whatever you prefer).
Heck, I like characters like Blaze and Wave, but I will admit I do see the point of the critics.
3D Sonic can be good, but Sega almost always finds ways to mess it up. Sonic Heros was way too complicated and gimmicky, Sonic the Hodgehog was just too buggy and not well refined, and Sonic Unleashed...by gosh, they almost had something. The fast sections were fine, but the werehog?WEREHOG!? You serious!?
Ugh, I can really only name three good Sonic 3D games: Sonic Adventure, Sonic Adventure 2 (both for the Dreamcast), and Sonic and the Secret Rings. Granted, neither were perfect or as good as the 2D adventures, but are fine games by themselves.
Sega just needs to keep it simple. The next Sonic does not need to be Super Mario Galaxy. Mario was made for jumping. Sonic was made for running.
Please don't screw it up Sega...