The basic gamefeel is very good, very responsive! It's unreasonably fast though. I had fun, but would have had more fun if the speed was a little bit slower. There were some checkpoints where you die in less than a second, and since the load times vary a bit, it made it hard to make those first jumps from the checkpoints.
I'd also make the camera follow the player with a little bit of delay so the visuals don't jump that much when going very high or low. Of course, with current tempo, it would prevent the player from seeing a lot of the traps.
There were plenty of great, creative level design choices, and the way the game suddenly turned into VVVVVV was awesome. The music was banging, it was a nice touch to restart it from where it was, not from the very beginning.