All right, a couple of notes:
– Dragging the paddle with your mouse is a terrible way to control it. It's hard to figure out and you have to hold the button for the duration of the game. Just make it follow your cursor position.
– When you have a magnetic paddle and multiple balls, all of them cling to you, but you can release only one
– I'd make some blocks take more hits to break (but slow the spawning accordingly)
– Every level consist of basically waiting until you get 'Super Ball' powerup, after which you steamroll through the level. This could be balanced by the bricks which take more hits to break, so even a super ball would bounce off them.
– The expand/shrink powerups don't expand/shrink the paddle very much
– Sometimes there are too many powerups onscreen. I'd limit the maximal number which can be there at a given time (to +- 3)
– Pause button doesn't work
– Getting 'Game Over' doesn't stop the balls, so you can get Game Over and Level Complete right after that
– Sometimes the ball bounces in an almost parallel direction with the paddle, which makes it take a really long time to get anywhere. I'd perhaps restrict the minimum angle to at least 15°-30°.

So currently, it's not a very interesting game to play, because controlling the paddle is really a chore and all the blocks are exactly the same.