Underneath the cartoonish graphics is one of the most addicting multi-player games you'll find.
In Fat Princess, there a 6 playable classes: The Priest, Mage, Warrior, Worker, Ranger, and Villager. Everyone starts out as villager, but changing classes is as easy as picking up a hat. Each class (except for the villager) can also be upgraded, making them more powerful. Now there are some balance issues, like the Upgraded Mage can freeze opponents, but it is so effective, you can easily just keep spamming it and keep your opponents from moving. The warrior has the most health, and once upgraded, can kill an opponent in 2 hits. But other than these, the classes are pretty fairly balanced.
Fat Princess has a single player story, but where it really shines is in multi-player. Thanks to a new patch you can easily jump into a game, and if there aren't enough players in a multi player match to fill up each team, the substitutes AI characters until more players come. There is rarely any lag, and the matches can drag on for a nice long amount of time.
In conclusion, Fat Princess is an amazing multi-player game with a nice bit of strategy. It is a great deal at the $15 price tag.