Maybe not the best interpretation ever, but my thought was that you can't go too fast, because you can't avoid the obstacles than, so sometimes you have to hit the spiky things ('failure') to lose some speed, but keep the most of it.
A tutorial would be good. I realized very fast that I will need to change between the players and control both of them, but it took some time to find the key for that. Also I didn't know about the transfering mechanism, I read that after I completed the game.
I would change the difficulty a little bit. At first spawn less obstacles, and than increase the count (by changing the time between spawns). This way it would be easier in the beginning, and harder later.