The controls were good, and the game wasn't bad either, however I'd rather write down the things that I think should be changed, because the little things can add up and that results in bad rewievs.
I think a 1st person camera might have been better than 3rd person. There should be more feedback that the ball is currently merged or not. Maybe a 3rd color or the two colors on each side of the ball would have been good. The add of physics meant that the balls are hard to get on the button. And the button was more like a switch so that took me a while to figure out.