Yeah, I have to admit that the UT3 demo entirely unenthused me. It just seemed to lack much soul, and is literally more of the same with better graphics; I can't see it being any less or more fun than UT if you're with people you know.
If you're by yourself it's cack and you just get wankered by these guys who've spent years perfecting their mastery of the UT craft. I do like to get good at games and the process of becoming better is something I normally enjoy, but this is so fast you literally can't keep up and it's just no fun at all when you get completely battered every time you encounter someone.
I have much more fun with something like TF2, but Worms remains my most anticipated. ;