I tried to play with mouse. It's very difficult to play cross court shots.
With keyboard, it's ok. But I believe the shots playing is not that realistic. e.g. when the player has to run far right and play a shot, in reality it's very tough to put the ball cross court towards the left. But the game makes it easy. Ideally, the angle of the ball should change dynamically depending on where the ball the hits the racket, the position of the player, running, etc. When this is implemented, I'll be able to put the ball cross court by placing myself strategically. You see what I mean? There are a few flash tennis games on the web that do this quite nicely...
This is a good game. If only the shot playing is more realistic, it would've been a great game!