This game is awesome. I love that it essentially just does one thing and does it well. Nice controls, smart tracks, endless replay value, and a good difficulty level.
However, ever since I got gold on all the tracks I haven't felt like playing much anymore. I think it's because the artstyle is so bland. It's especially disappointing coming after Mos, which for my money has one of the best visual styles in the AppStore. I realize it was probably a conscious decision to keep the art simple to match the gameplay, but I think there is an important distinction between simple and just dull.
In short, this is a fantastic game that is a steal at 99 cents, and it'd easily be one of my favorites if only it were just a bit easier on the eyes.