The art is really cool, I am really enjoying the background. The high-score board was very well done as well.
BUT! The levels did get pretty boring after about 5 levels. The flat landscape just wasn't doing it for me.
I tried (and failed) to make a similar game(dl.dropboxusercontent.com/u/240730800/Pinwheel/index.html). I made the terrain random, and the positioning of the spikes and plants as well. The game uses the same controls as your game.
Also the font for the in-game HUD could have been better, and the name of the game is excellent.
Overall, good game. I rated 4 stars. I see a lot of promise, and hope that you don't quit(like I did).