Good concept but aggravating movement
The left-right acceleration is really slow, making it way harder to control and making it seem as if the character is sliding on ice. Platform games are better without this "slipperiness" - pressing the left button should make you go left, the right button should make you go right, and if you press neither you should instantly stop.
This wasn't so bad in the first few levels but it's really noticeable (and aggravating) when you have the puzzles that involve precision jumping over spikes with a 5 second time limit and a looooong walk back through the underworld if you misstep. Giving up on the game because of this.