Just got done playing through the first boss. It's definitely the best Sonic I've played in a while (post-Genesis), but I'm far from giving my final verdict.
The "cheap deaths" I've heard professional reviewers claim aren't cheap; there's even a little hazard sign that pops up when you're near a bottomless hole.
The controls could be tighter, and I think a better tutorial would've helped. There's a tutorial giving help when you ask for it, but it leaves me confused with explanations that say "use the boost button"--okay, which is the boost button?!
The manual kind of tells you, but the format could be easier to understand.
Anyway, I've found that I like the Classic Controller/Pro over the GameCube and the Nunchuk combination, but I haven't used the Wii remote sideways yet.