Really liked the game! I beat it and even got the secret reward at the top of the tower.
Unlike some people on this thread I really enjoyed the difficulty curve. The fact that i couldn't even jump at the start really hooked me in and separated this game from other mario-ish platformers I have played.
One thing I wish I had was the option to toggle "sprinting" rather than holding down the run buttons. I played this game for quite a few hours to get nearly 100% and most of that required constantly holding down the sprint button. My fingers got pretty achy near the end.