Previously, this app was broken in that it basically did nothing. It now works. Yay!
As for the game itself, I have one single complaint; if you get going too fast, the music cuts out. (According to in-game tips, this is intentional.) I'd prefer if the music got MORE intense if you broke the sound barrier, not less.
Aside from that, it's a unique, simple to learn, tough to master game, and I love it.