Great game! Controls are a little sensitive and from observing the other players they are having a lot of fun with just trying to blast the ball into oblivion! Unintended consequence that generated lots of player retention! A happy accident as it were
Add some sound effects and visual effects when the ball hits the paddle to make it more satisfying. Think of ways for the player to challenge themselves. A highscore is an easy one but can you think of anything else?