I think the general gameplay here is pretty good, and the pixel art looks nice. The game could use a bit more of a tutorial or something though; from what I could tell, there weren't any instructions or anything for the controls or how to play (after I got stuck on the first screen, I had to assume there was some control I was missing and blindly hit buttons until I found the dash button).
Related to that, there wasn't really any easing into the difficulty of the game. If you were going for a Super Meat Boy-style precision platformer, then that could work, but if you were looking for more general appeal then I'd recommend reducing the amount of hazards in the levels. In particular, the horizontal hallways of spikes that you had to dash through felt a little too precise for my liking, especially when there's one at the end of a level. Maybe my technique wasn't right, but since there's no real tutorial in the game, I wouldn't know.
Fundamentally though, this game is solid; my critique is more with the level design than anything (although you might also want to look at the font you're using; I could barely read the text in the intro cutscene).