I really enjoyed the way the game unfolds as you progress. The flipping mechanic is pretty cool, though it's a bit weird at times since I have to flip while facing one perspective and then change to a different one to get to some places.
Without repeating too much of what others have said, the collision is really weird, especially with jumping, and I can see the collision shape at times. I also noticed that the font for the first level complete wasn't the same as the others, which I imagine is unintentional.