Nothing really new to the game but still a lot of fun!
First of all like i alread said , if you know UT2k3 or 2k4 you'll know the basic formula of UT3. There are some slight changes in the weapons and in the movements of your character but that's basically it.... there are a few new game modes which i don't really feel like explaining them right now.
There are also a few modes gone like Assault and Domination which i think is pretty dumb since it won't be that much of work for the developers to do in my opinion.
The only real bad thing about UT3 is probably that i still miss the community UT'99 and UT2k4 had , lots and lots of people and many servers. I don't really care about the servers but sometimes you come online and there are only 1 or 2 servers with a good ping in Deathmatch mode where there are people to play with.... and that really concerns me but that leads me to another bad thing about UT3...
There are not really interesting maps in UT3 , maps are often really small with narrow corridors and on top of that, there aren't that many maps which will lead probably lead to getting sick of playing that same map over and over again. You can play a map a very long time if you like the game but still the lack of variety will get you quit the game.
So without a real community there aren't many maps coming out and there aren't many custom maps on servers but maybe that'll change , if you think you want to play a fun Multiplayer game, UT3 is something for you!
p.s. : If anyone isn't sharing my opinion and has questions just pm me :P