The game is simple to play but very hard to master. If the moving balls were not enough, there are gravity and repulsive effects and speed changes that can catch you off guard.
I enjoy the game play, but it is so easy to collide with a red ball there is also a high frustration factor. If I could make one suggestion to the author of the game it would be to have the red balls take a percentage of health instead of instant death. Of course, the way it is makes the game more of a challenge. I may just be too much of a wimp with slow reflexes.