Well, you've made a fully functional game, which is more than I can say for most other creators; I would gladly take "bare-bones and functional" over "broken with a million bells and whistles" any day of the week.
My one big complaint is that I wish the paddles and maybe the puck were just slightly larger. You have a lot of real estate here, and your paddle takes up so little space on the board that it makes it hard to get good contact with the puck. Another thing that I think would benefit your game is the addition of center and crease lines, just so you have a reference for how far your paddle is allowed to go up and down the screen—I personally had a hard time telling how far I could go from time to time, which really messed me up.
Aside from the minor glitch that causes the puck to clip inside of the opponent's paddle, you created something pretty solid here. The fact that the AI speeds up according to the force you strike the puck with is really something, and adds a bit more depth to the game than just "enemy player moves incredibly fast, and you can't score against it no matter what you do".