Not so great, because success is very self-enforcing. The first 15 sec usually decide if you win or lose.
Small issues: sound off isn't saved through levels, english translation needs proof-reading.
"None of the levels require you to move at super human speeds."
The last levels definitely require a lot of timing. I beat the last level through a glitch though (you can get the ball to bounce into the exit by switching between red and blue repeatedly.