Short and sweet. I really like the sound effects you used. I was not expecting the intro, I liked it. The biggest issue is the length, but I'm pretty sure you know that. Also, the controls are a bit counterintuitive, maybe you should make it so you can jump with the arrow keys too. It was fun tho.
oh, and I think it would be better if the echo weapon bounces off the walls and floor, that could gives the game more variety and would fit the theme a bit better.