I feel the movement is too fast or slippery for the precise platforming necessary in level 9 and 12. The only reason I got past level 9 was I found the shortcut. Other than that, it's an addictive game and I did manage to finish it.
Edit: there is a bug where it does not recognize that you finished the game if the last spike ball explodes while already standing in front of the door. That made it a little harder for me to get platinum on level 4. I still got it though.