Unreal Tournament is best played online or at Lan parties, the solo side of the game is an introduction to showcase what the game/engine is capable of.
Since the game was released, there as been 3 patches and a bonus pack, and lots of quality user created content, which as put the game into a nice prospective.
The Unreal Editor that comes with the game is mind blowing with what it can do, and if you get the Limited Collector's Edition , it comes with video tutorials to show you how to use the the editor.
You can also make content for which can be converted to the Playstation 3 version of UT3.
For £17.99 the Collector's Edition is fantastic for its money.