I liked the art, and the concept of both the timed switching and the "making stars" plot. The sound was also pretty good. I do wish the spikes were also pixel, but that's fairly minor.
My actual problem was the slippery controls, however. When you stop, your character slides way too far in the direction you were just moving. This makes almost every level way more difficult and annoying to play, since your character slides off of platforms when you want them to stop.
Still, despite that major issue, the game was still fun, it just needs some more polish.