There are a few things that can be improved with regards to this game.
Firstly, the overall motion is quite jerky and sometimes makes gameplay a little annoying. Also, after a small amount of time, one can easily get into a loop where the ball follows that exact same path and every time the computer AI just misses it. One can therefore simply keep the paddle in one place and your score can just go up indefinitely.
I recommend that you put some randomness into the bounce of the ball (about a margin of 15 degrees or so) as well as make the gameplay more smooth. You could also try to make the AI a little more unpredictable. Music and sound effects would also be a nice addition.
I checked all the medals and they do work. Otherwise, the game itself isn't too bad; I haven't yet picked up any major bugs or errors. If it is your first game using ActionScript, then it's not too bad (I've seen much worse pong games).
The addition of ball sizes, speed and medals make me give you a total of 2 and half stars for the game.