Great stuff. Only beef I have with this game is that I felt I lacked some of the tools for "precision control" once the spikes are introduced. It felt like I have to put the cartrige in and out just to sync jumping and walking from time to time.
Might be a simple level design problem, and might be a simple "I am an idiot that missed something" problem.
Either way, I really like it. And the music and SFX are just so perfect for it.