Didn't see a thread for this one yet, and I know there are some Sonicphiles on this board. I picked this one up yesterday and wanted to see what others think, in addition to offering an opinion of my own.
Sonic and the Secret Rings is not quite the "return to form" I was expecting (and hoping for) but it is definitely the best game of Sonic the Hedgehog since the Sonic levels of the two Sonic Adventure games. The annoying "attitude" Sonic developed when he moved to the third dimension is here in full force, but the thematic setting (Arabian Nights) and level design are a move in the right direction.
The graphics are quite nice, the soundtrack is horrendous ("so bad its good" to some), and the controls require some adjustment, but are generally intuitive and responsive (I like the jerk forward for the homing attack actually). Sonic is constantly in a state of forward motion, but ceases to feel like a runaway train after a couple of plays. It isn't perfect, but it works. Actually, it would make for a sick Sonic R styled racing title and reminds those who have played Sonic Riders how abysmal that game really is.
The biggest problem I have with the game is that there is no continuous story mode. Ala Nights into Dreams, you are thrown back to a menu upon completing one of the many varied stages. I am not pleased with this, but the gameplay makes up for it for the most part. It also could have used a bit more focus on the straight run-through the level stages rather than the various missions within levels that have you completing the stage over and over with different conditions for victory. None of the missions are anywhere near as fun as the straight up speed runs and boss fights. The RPG-lite power-up scheme for Sonic, and the multiplayer, which consists of a bunch of minigames, both feel totally tacked on as well. All of these things don' break the game, but it isn't as good as it could have been. If the game had a bit more focus, it could have actually been stellar.
Regardless, it is nice to have at least some of the bad taste left by Sonic Heroes, Shadow the Hedgehog, Sonic Riders and the 360 Sonic the Hedgehog washed out of my mouth. I can't bring myself to recommend Sonic and the Secret Rings, but it is certainly not the worst game you could buy for the Wii. A must have for the long suffering legion of Sonic fans, but a rental for everyone else.