I think that overall it was pretty good, definitely addicting. I think that running into rocks should either kill you, or more heavily impact your speed. Also, while using the speed boost it is incredibly difficult to dodge the rocks, I would either make it so they spawn less frequently during the boost or give the player invulnerability during the boost.
I also feel that variation would help out a ton, right now the only obstacle is rocks, I think some variation both in obstacles and player moveset would help out.