Loved teh song selection, and unlocking the next and the next kept me playing. (only takes about 30 minutes folks to play them all so far)
The first time I played I died at about 5000 points in and thought, "whoah, this is hard" but then my eyes adjusted to it and after hiding in the corner for the next couple songs, I got the hang of it and I think the difficulty is perfect. I can play it safe and stay at full health, or risk it for those flashing squares and try to balance them with green squares.
People who are saying its too hard obviously are used to their Wii games or something.
I found myself tapping teh arrow keys to the beat a lot while dodging haha, sorta like the old coolio game "Streamline" remember that one?