I haven't played this game, but I heard that the day stages are great (I think the lack of them in the game is due to the stages taking a long time to design). So at least SonicTeam are improving in that regard- they know what they have to do now, it's just a question of putting enough effort into the game and not to ruin it with a silly gimmick (guns, lol).
But indeed, the Sonic thing is wearing very thin now, and I totally agree with cool. Whatever happened to Ristar!? There are so many games that should be remade.