i love it!
simple, fun, and addicting; and it's a concept that I haven't seen before, so you get points for originality too. I really like the atmosphere of the game: graphics, music, everything.
a few minor problems: if i don't unlock the next track and press 'next' instead of 'retry' then it takes me back to the first level. Also, on the last track, the grass starts to disappear before it's completely off the screen (play it and you'll see what I mean).
All in all, it was fun! :D