I'm not a fan at all of tennis as a sport, and I usually don't ever play tennis video games. Only other tennis game that I've played(that I can remember) is Mario Tennis for N64, which I had a lot of fun playing with friends. When I got my DC my friend gave me his old games, this being one of them. At first I just planned on selling it seeing as I wasn't interested at all, but I decided to give it a quick try before to see if I was missing anything, and let me say, I'm glad I didn't sell it.
The gameplay is pretty basic, you move around the court and have two buttons to hit the ball with, one for a normal shot and one for lob, then you can also control where you hit the ball to with the joystick or d-pad. Playing this game on exhibition can get kinda boring, even with some friends. This isn't where the game shines, its in the deep World Circuit mode.
When you start the World Circuit, you start off ranked really low in the rankings and have little money. You do different kind of challenges which are like mini-games(bowling with serves, lobbing balls into buckets, etc), then also play different matches to move up your world rankings and earn money for new items and doubles partners. There is a whole lot to do in the World Circuit, and will keep you occupied a damn long time before you reach the #1 world ranking, and manages to stay varied in the gameplay and not get repetitive over the time.
The AI in this game is really good, and gets even smarter as you play on harder difficulties. Each player has their own playing style, and will adapt to yours if you don't vary your playing style throughout the match.
Graphics are really good with some great animations. The game sounds really good too, but neither of those are that important in a game like this.
This game is definatley worth a purchase, with a great transition from the arcade to the console. The World Circuit is great fun, its great to switch off with a friend trying to get the highest ranking you can. Considering how cheap you can pick it up for now, its a must-buy!