I'm not sure exactly how much I like the game (the upgrade process becomes painful later on, but that's in line with any upgrade game, I guess). But the song is surprisingly awesome.
I'm having trouble unlocking daisy at the end (it seem to go into another screen where I see daisy and she can hit me, but I don't lose life, and it doesn't seem to go anywhere else). Other than that. This is a really beautiful game.