It was actually rather fun. It's a very simple concept, yet it's terribly addicting. Just trying to get the high score (Which I did get) was really fun.
The art isn't very good. Most of it is the green gradient that is on the color picker in flash. I think it would have looked better if there was more solid colors, honestly. If you made the bricks/stone wall either Grey or dark red it would have looked quite good.
I encountered a glitch, although I'm not quite sure how I did it. I grabbed the ball and bounced it and it went near the top of the screen and continued bouncing. It slowed down, so it would be a very slow way to get a high score, but a really high score could still be obtained by doing it.
I think your score should go up every time it bounces off a wall, and it continues going up until it completely stops. That would make the game a lot more fun in my opinion.