The concept is a bit simple - just press space as fast as you can, which I think isn't very fun, but I can see some people like this kind of thing. It's too easy though, even on hard, and once you've passed the opponent you can just tap space slowly to keep the tempo up.
I do like the music and the visuals very much though, so 5 stars for that.
I think with a bit of tweaking, to make the difficulty a bit tighter, so you actually have to fight until the finish line, this could make a fun game!