who said hard wasn't fun?
Graphics: Though a game shouldn't be rated by it's graphics, UT3's graphics add immensely to the gameplay, bringing violent bloodshed into your living room, looking 100% real.
Gameplay: The confusion you might first experience can be frustrating, but after playing for a couple of hours, you will find the game to have plenty of meat, presented in a nice manner. Plenty of guns, plenty of ways to shoot them, plenty of vehicles, plenty of things to do with them as well. Bots add to the replay value as well as the playing value, since you no longer need to buy an online membership or have someone over to play with you, however, this doesn't mean that playing with another human isn't fun, on the contrary, it adds to the game.. Lots of maps and plenty of games modes add to the immense variety, making each match different. The controls are easy to learn as well, what more could you ask for.
Replay/Don't stop playing value: Very high, you may very well not stop playing this game.
Conclusion, this is money well spent, great gameplay combined with much variety and the ability to play multiplayer with only one person make a great game, definitely one you should buy.