Simple, beautiful graphics and gameplay. Great atmosphere. Boring AI opponents and almost nobody online to play against.
It isn't a complex game, but some great games against real people would be enjoyable. Last time I checked, there were probably two dozen people online and only three or four actual games going on. This would make an excellent XBOX Live Arcade game and would draw a lot more people into the competition.
If you have someone to play with at home, buy a copy or two and play via LAN. Otherwise, realize that you may not get a lot of gameplay out of your $20 or $30.