1) At even Junior level and above, the computer is too easily able to hit perfect shots on the back foot. Meaning, I understand how good they are and should be when serving, hitting normal strokes, etc.; but when I hit a perfect serve or shot, they should be on the defensive, if they even get to it; instead they often hit a flawless, impossible shot crosscourt--thus making the skill level of the human players' shots irrelevant.
2) When you are facing a player at the net (especially a computer player), one of your main defenses should not have to be a lob. In real tennis, lobs almost never come into play--watch a pro match and tell me how many lobs you see. Instead, passing shots should be much, much more effective, especially if you have time to set up the shot. Passing shots are a huge part of tennis, and so satisfying.
3) For me, gameplay is vastly more important than ultra-slick graphics, but there are a couple graphic improvements that could be made to improve the overall game. For example, when running backwards to get a lob, the player could actually turn instead of always backpedaling; and if the player gets to the ball in this situation, the ball will be hit without him even swinging the racket. That happens sometimes at the net as well. This might be stretching it, but players diving for balls would really add a lot to the game, too. Being able to select a few different hairstyles (bald, long hair, etc.) when creating a player would bring more personality to new players. Also variations in height would be a huge step up.
4) Sometimes your player will freeze, unable to move on an opponent's drop shot, when the ball hits the net and comes over to your side, and occasionally on a very easy lob. Also, when playing doubles with the computer, the computer is a little too easily confused by your movements and sometimes will let a ball bounce right past him.
5) As for controls, I would #1 recommend switching drop shot (both buttons and up) with agg. lob (both buttons and down), as it would make more sense. *Or, how about this: button #1(B1) is hitting the ball normally. So holding up plus B1 would be a normal speed deep shot straight up the middle, up+left+B1 would be a normal shot to the deep left, etc. Button #2 (B2) is the lob/drop shot button. So, B2+up+left would be a lob to deep left, and B2+down+right would be a drop shot to the right. Both buttons together (B2+B3) is the power top-spin shot just like now, except the player can now direct it better to the six corners of the court using the arrow keys/direction pad. My purpose in proposing the switched buttons is to create a system that gives a player more control over his shots, and more natural feel to directing shots. Also there would be less memorization of button combos. The only downfall perhaps there is no place anymore for a slice--but that could be easily figured out, perhaps by using B1 and down plus any direction, or even a third key.
6) When a ball is travelling out, I think it would be more realistic and challening if your player did NOT automatically let it go IF you hit the button. Of course this would only come into play when you are at or near the net. This would force the player to judge the ball on his own, making a new skill for players to develop. Perhaps this would only come into play on more difficult skill levels.
7) ONLINE VERSION FOR MACS!

