Good... needs work.
The overal game was good (despite the fact that its been done a million times), but there are a lot of little bugs adding up, especialy with collisions.
The ball can go through the edge of a brick, this can be exploited to destroy entire rows
Sometimes when the ball hits a brick that causes it to bounce in an unexpected direction, it bounces INTO the rest.
The ball can get stuck in an indestructible brick, try making them
breakable but requireing an insane number of hits (50, 100...)
The missle attack only destroys one of the bricks it hits, it should at least destroy one for each missle
The fireball barely has any explosive effect, it is hardly better than the regular ball, and the ball that goes through bricks is too common/powerfull
It may be a good idea to have the multi ball powerups split all the balls