The game itself is solid but there arn't very many people playing online because most have moved on to more recent games. Those that you do find playing are usually people from other countries who don't have the means to upgrade their machine, or people who run linux and this is pretty much the best game port they got. So your selection of matches is rather limited, often most of the people in the match are infact bots.
Once you do find a game the action consists of two characters jumping around each other alot and hoping they hit first with their weapon. Unless you closely follow the quake/unreal games this will seem very very odd to you, especially since most other shooters are more tacticly driven, even those that are totaly unrealistic.. Also if you've never played this game before you will get your ass handed to you again and again, because just about all of those frequently playing, have been frequently playing for a long long time.
If this was your game in its heyday and you feel the need for some nostalgia, by all means go for it, but if you've never played a UT game before I suggest staying away from this one.