A great tennis game for those willing to learn the control scheme and put-up with a few quirks.
(a) the patience to learn (and get better at) the Wii Motion Plus controls
(b) acceptance of the fact that once in a while, you're going to have a frustratingly screwy response from the controls
This is not a "pick-up-and-play" type game and that's the reason for some of the mixed/bad reviews out there. It really does take a couple days of play before it all starts to "click" and you can start placing the shots where you want them. However, to get there, there are a few undocumented aspects of the control scheme that must be learned and (unfortunately) they're not made clear in any of the instructions/tutorials. The most important of which is learning to "center" your racquet in front of you, facing the screen, after every shot. This method really helps keep the controls in-check MOST of the time. But, as mentioned above, once in a while, you'll still have a situation where the AI swings for you unintentionally or (if not using the Nunchuck for movement) will have your player over-run the obvious location for your shot.
But, those glitch moments become less-and-less the more you adapt to the controls. It does take constant concentration to be good at this game (but, so does real tennis).
If you want a rich tennis experience and are willing to put-up with the high learning curve, you'll quickly find that GST is extremely addictive and fun.
I give it an 8.5 for this first edition, but if EA can improve their control scheme in the future (perhaps provide some user-changable control tweaks, improve the tutorials/instructions, and remove the once-in-a-while glitches) they're going to have a great future with this new franchise.