Unlike the major sports, Tennis gets very short shrift in the videogame world. One would think it's probably one of the easier games to program, however given the lack of tennis titles, it's either very difficult or not profitable.
A few years back, Microsoft released many sports titles under an "XSN Sports" moniker. There were online leagues and it was a very slick interface. There was only one problem - the games didn't sell that well (one of which was Top Spin) and Microsoft gave up and sold off their franchises (Top Spin, Amped, etc) to 2K Games. 2K Games realized that there weren't many tennis games out for the PS2 and set about porting the Xbox Top Spin to the PS2.
If anything, this game proves that it's difficult to port 'down' instead of up - it's easy to go from the PS2 to the Xbox, but not so much the other way around.
Basically if you've played this game on Xbox, there is nothing new and no reason to purchase this game. On the other hand, if you've played the heck out of Sega Sports Tennis from all those years ago, and want a new challenge, you could give this game a whirl.
Starting up the game, you have four options: play an exhibition (singles or doubles - you can have 4 human players here which is a neat thing if you have four players who like tennis). You can also start up a custom tournament with up to 15 humans, which is a pretty neat idea.
The other two modes are probably where you are going to spend the majority of your time: online and career. The career mode is very similar to the old Sega Tennis game with some added flair - you have sponsors to give you additional cash for example. The career mode is spent playing mini games, purchasing new items for your player, going to salons to get your haircut (seriously), and improving your skills.
In the career mode, you can really customize your player and big kudos to the 2K sports team for allowing gamers to use the Eye Toy USB camera to put their face in the game. Although it seems gimmicky, I was surprised at how well it worked. There are plenty of attributes to modify in your career mode (DNA for example) as well. You can choose whether your players favored hand, hair color and all the usual customizations.
The online mode is well done, except on three different occasions I was unable to find a player for the game. It seems disappointing that a game that has only been out for about a month does not have many players online, especially with such a nice setup. The PS2 version is run by GameSpy, which is familiar, but I still prefer the Xbox Lobby and webpage over the PS2 version.
Let's talk about the game: the actual gameplay is pretty good. The ball physics make sense and you can get a good read or feel for where the ball is going to go and how fast it will move based on the way the player hits the ball (ie forehand or backhand). It is very well done. The control allows you to hit six different shots, including a drop shot and a risk shot. It's called a risk shot because it's risky. Instead of just timing your button press on a risk shot you have to hold the button down which displays a risk meter. You have to release the button when the meter is right in the middle. The better your player is, the slower (and the easier) the meter is. If you get it right in the middle, you'll hit a very powerful shot. If you don't, your shot will probably go out. See, that's a risk and therefore it's called a risk shot. The CPU's ability does vary by player. There are really bad tennis players and very good tennis players. As you can imagine, the more you play, the better you get as well.