The game was too small for me, and I found myself squinting to see everything. The controls and collision were very good, and there's a lot of potential but I'm afraid I agree with the other commenters about it being frustrating. Restart points would help a lot.
I think part of the problem was the speed the character moves at so maybe making the jumping/ gravity lower to give more control when falling, which would remove some of the frustration I (and others?) was getting.