i think Shadow was the worst SEGA game ever made... it's the only Sonic-related game i can't even say ONE good thing about...Sonic 3&K. Of course the last sonic I've played was Shadow and that was absolutely atrocious.
STH4 looks like balls. it's a complete rehash of STH2, basically identical level themes. i've seen some rough reviews on it's physics too.
however Sonic Colors actually looks pretty fun, looks much like a real Sonic game, with platforming! if i had a Wii, i'd try it. Unleashed looks lame to me, i don't want to play as a were... hog... i want to play as a damn hedgehog.