Actually pretty fun, though only when you're going at a straight line since it keeps the players attention the whole time and focus on when to press spacebar. When it runs diagonal however, you'd simply have to press the button once and wait 10 seconds before having to go down again, making the game a bit boring like a long geometry dash level.
You could also perhaps add a trail of sorts to the ball for when it's moving to get a real nice sense of motion.