Very competent! The controls, if a bit strangely mapped, function quite well. The level design was pretty good. The last level had some clever precision platformer design; even when I failed, I understood why I failed quite clearly!
A couple of notes about the audio: holding down the menu buttons seems to repeat the sounds, causing them to stack on top of each other quite loudly. Also, the menu and death sounds are a bit louder than the other sounds.
As for as control schemes, I think adding the arrow keys for movement, Z for jump, as well as right-side keys like J or K for the jump and dash, would do a lot for the keyboard controls. If you want a good "left-hand-only" scheme, I would recommend adding LShift to dash as well.
Good work!