It's made by Sting, the Riviera and Baroque people. They're porting their PS2 games to the Wii and Atlus is publishing both at the same time. At least, that seems to be their strategy.
Everything I've read says that the only new things are better graphics and anime cutscenes. Not worth the year long wait, if you ask me.
Oh, and those minigames from the GBA ones, but who's counting them?
I pretty much play Super Smash Brothers Brawl everyday.
I don't really play many games after I beat them. There was a time when I'd do the New Game + modes in some games, but nowadays they fail to keep my attention.
You have to complete all the hunts and defeat Hell Wyrm.
The best part is you can leave and come back and he will still have the same HP as you left him. So you don't have to beat him in one sitting.
Then Nintendo would have revealed their hand far too soon. If they announced Sonic now, how could they top it?
That, and I think Nintendo would have him as a Hidden character; not even hinting his existence untill the game is released.
A quick seach on GameFAQs revealed That you're supposed to shoot a charged Skull Storm into the opening in it's head, then he opens his lower body again and the pattern repeats itself.