One word.. shocker. I feel in love with the game when I recieved it on a demo and I rushed out to get the full game. This is THE best tennis game ever made. The one player World Circuit was cool... with its mini challenges and kept me hooked. The doubles is amazing and when playing in multiplayer mode, this is where the game shines. This is the best multiplayer game on DC. The game is true to the physics of the various courts and the players move smoothly. The controls were bliss and allowed for easy pickup and play. Sounds were pretty decent and the music kept the adrenline pumping.
The graphics could have been improved on, an option of 2p mode for the World Circuit would have been great, and a current roster of better known tennis players would have been a bonus. (but I guess that's what sequels are for).
This game is a classic and defintely earns its title as a sleeper hit. Undeniably the best tennis game ever and one of the best for the DC, go pick it up.