Great online, beautiful game, exiting controls even if deceptive from time to time. The best tennis game I ever played.
I played around 50 hours to GST (so far), probably 25 hours alone, and 25 hours online (around 90 plays), and I will keep playing online. Today, around 100 players are connected anytime, it takes 15 seconds to find an opponent. With few exceptions, there no lag when you play US/Canada. A small lag when you play Europeans or Japanese.
The game is really poor in play modes (no decent carrer mode), but the online saves the game.
Controls (I play with WM+ and nunchick) are highly immersive but can sometimes be frustrating. Right and left are easily manageable, but i have low success in getting the lift or slice I wanted. Despite this lack of full control, GST provide a feeling I had with no other tennis game.