I've been a UT player for many years, and though I've slacked off of late, when the new UT3 demo was released I had to take a peek.
Install went OK, but there were huge amounts of registry modifications due to the included installation of the Microsoft.net framework. I think that installing the .net stuff took longer than installing UT3!
Trying to run UT3 demo failed at first, and the problem was my graphics drivers. So updating to the latest version solved the issues and UT3 would launch. At first I was just getting a feel for the performance while wandering through a few maps alone. Graphics are pretty nice looking, though underwhelming compared to the many screenshots released in previous months. Performance on my older machine is surprisingly great. Irritatingly, when there is a crash (this is a BETA demo) I'll usually have to reboot before I can play again.
Last night I got my first real gameplay experience. I ran a few vehicle CTF maps against bots. The action was very different from the UT2k series, but very enjoyable. Action is fast, but not frenetic. Weapons feel reasonably balanced, and have a good variety. In my hour of play, the bots seemed to manage well and made use of the weapons and tools nicely.
Looks like a good start.
Link to the official site:
http://www.unrealtournament3.com/
UPDATE: I found why the performance on my machine was so very nice. There is a slider in the advanced video options that controls the render percentage. By default (the settings I was using) that slider is at 50%. Setting to 100% not only greatly improves the image quailty, but puts a much larger load on my machine.