The game play of your game is very good and I'm really enjoying playing it. The only problem I can see with the CPU AI and gameplay is that sometimes when you think you've hit a shot that will be difficult for them to return they seem to strike the ball as accurately and powerfully as any other shot and still be ready to receive another return instantly. Instead a real player would maybe stretch and miss hit or at least hit a weaker, slower, lofted shot back and struggle to recover. Is this something that will change for 2007? I hope so as this could be the icing on a very tasty cake!
A good example would be in Virtua Tennis when a player will stumble almost to reach a wide shot, returning it poorly and take longer to recover for the next shot. Of course your game has numerous advantages over the arcade style VT.