The game is ok in my opinion. The tennis were alright and the special for each character were neat. But, I didn't like how the tournament was. All I'll say is, that when compared the the Mario Tennis, this one doesn't match up. I sent it back the same day I received the game. I didn't want to waste more time on it.
I downloaded the demo on the PSN, and really that demo is exactly what you get in the full game. It's fun for a few matches, but the mini games tend to be very redundant. Basically, you unlock mini games that include running around collecting coins or hitting tennis balls into things. Fun, just no lasting replay value here. The only real excitement I got with this game was playing against another person (not AI).
I attempted to play online once and had no luck. I must have literally been the only person online trying to get a match going.
Fun, worth getting from gamefly, just not worth a purchase.