Not bad.
However there are areas which should be fixed. When you click to start the ball going you should have it launch from thr paddle instead of midscreen, it cost me a few balls. You should have speed gradually build up in the ball, because it moves pretty quickly in no time, and cost me a few balls.
Give the player time to learn the speed of the ball. The simple presentation was good. I liked the 3 color backgrounds. Very simple,kinda stylish, and it fit with the music.You should have at least 3 or 4 tracks instead of one, by the way. That one song gets tired really fast.
Next time you might want to make the graphics cleaner, maybe make the backgrounds nice, clean, vector art and
the blocks,paddle and such,simple two-color objects,and when you hit the blocks, they could fade to white and dissapear, like the whole thing is played in a virtual environment. I could go on and on
about things you could do to improve this, but I'll stop here, because I've talked to much already.