I encountered the same problem as Jetsy and was unable to continue past level 3.
Level Design
There are quite a few levels. The tutorials were nicely done (missing tutorial for reset with "R"). Some mechanics, such as the wall jumping on one wall, could be explained in a safer environment, where the player could learn it better. The levels feel a bit chaotic sometimes (not a real problem) and monotone (more tile types would help). It would be nice if you could see the total number of coins so that it works as a collectible.
Mechanics
I feel like the wall jump mechanic is unnecessarily hard to do, making the game sometimes infuriating. The cloning was a real head-scratcher sometimes, which is good. However, in one instance I left the game running and came back after a few minutes and was unable to reset the "recording" of the clone (tried saving, going through doors, etc.). I finally fixed it by going back through the door, dying next to the door on spikes, going through it dead, and saving in the next level.
Audio
The music was nice and not repetitive, which is hard to do. The sound effects were also nice, however, I feel like some of them were louder than others, for example, the moving platforms.