Objectively probably a pretty bad game, but I have a weakness for Pong-Games and my first failed attempts at making games were also in Scratch. So I'm impressed you managed to make fully functional game in Scratch at all.
Anyways, constructive criticism: It's really simple to cheese, because the ball always travels back to where it came from. Some randomization would be good. Also you could introduce a broader zone near the middle border, where the pedals can't move to.