Full Ace Tennis is an impressive project for an indie developer; a serious tennis sports sim. It's in 3D -- low polycount by modern standards, but quite sufficient to impart a sense of verisimilitude -- and with a physics engine that does a good job of replicating the look and feel of the actual game.
Emphasis is on the world 'simulation;' you must position and time yourself accurately to return the ball, and controls allow you to select between back and forehand, top or back spin, and so on. Indeed, it's the kind of game where you need to train to play it effectively, which explains why there is an exhuastive tutorial.
Other features include a tournament and season mode, online play, a database of 400 tennis players with an editor that allows you to add more, and 40-something stadiums. Only one stadium and two players in the demo, however.
On the whole, it is an impressive product, about which I would be more enthusiastic if I gave a rat's ass about tennis.