Very Well Done
I bet it was a bitch to create a 3D thing like that on flash. Very nice indeed.
A couple suggestions to improve it:
1. I thought that it was a little easy to hit the ball. I think that the ball should gain more velocity going to the side when you hit it so it bounces around more side to side to make it more difficult.
2. It wouldn't really be nessecary but it would improve the game to have different speed settings for the player to increase or decrease the difficulty of them game. Another good option would be to have it start out slow then speed up gradually.
3. Make the background a little more interesting. Maybe have multiple backgrounds where the player could choose which one he wants.
4. Add more sound to it to liven it up a tad. Maybe a simple arcade musicy song in the background.
5. Put a scoreboard up in the game so you could tell how many hits you made.
6. Fake Britney Spears porn pics. Would get the game instantly voted to #1.
Just a few suggestions there. Use them as you like.