Oh wow. Nice.
This is one of the funner games I've played today. Let's see.
The music was a great choice for what you wanted, catchy and addictive. It did get a little tiresome after a while, but not enough to make me want to stop the game.
The graphics were simple, but for a game like this that was a good thing so over-all they served their purpose well.
A few complaints I have are:
1)The ball can be saved WELL AFTER it went past the blue bar, just by clipping the back end of it. Maybe fix it so that when the ball gets 3/4 past the blue bar it can't be saved so the game isn't super easy.
2)With such a plain background(don't get me wrong, it was good for this game) it was hard to have landmarks for where exactly the blue bar would appear at times to save the ball, maybe place a very faded image of it in the background where it will appear so you know what you are dealing with.
Also the game got a little boring after a while, so maybe try adding new features. Say increasing the over-all size of the canvas and giving more space for the balls to move around, then have random little power ups like. Double Balls, which create two balls that fly around at the same time to make things more difficult. A speed up/slow time thing for the balls to add some variety. Just whatever.
But don't get me wrong, this game is perfectly fun without power ups, so it's not a /needed/ thing.
All in all you've made a fun game and I hope I see more like it in the future.