I really liked UT3. It had its flaws, and still does, but they were mostly in the shoddy finishing touches that make a product feel polished. Core gameplay is mucho fun.
However, though I don't usually consider the surrounding circumstances when I rate a game's merits, I admit I was severely turned off of UT3 by Epic themselves. Their launch and treatment of the community were and continue to be so heavy-handed that I began to have negative associations with UT3. They were so defensive about it, and tried to hard to silence the flood of legitimate criticisms, that it very much gave the impression of a damage game from the days of the disastrous "beta demo". "Pay no attention to the man behind the curtain!" doesn't work very well, it seems. Seeing the high quotient of forum scrubbing and message control on Epic's official boards was the last piece of it, for me.
So, though the gameplay is good, Epic has nobody but themselves to blame for the awful reception Ut3 received. Many mediocre games have very strong communities, and the major factor seems to be the parent company's culture, and relation to their fans. Epic seems to feel that it can treat its fanbase however it pleases, and that it can survive by engine sales alone.
I loved UT3, but have not really played for three months now. Since I played every other UT game non-stop for nine years, and UT3 is easily their equal, I have to figure that there's something else that turned me away from it. So don't judge the gameplay by the awful online presence, or the negative vibe on these boards. Epic has shaken off a large portion of their loyal UT fanbase in these past six months, and is likely hoping for a new community based on UT3, who doesn't remember the company they used to be. Good luck to them with that, and if you like UT3 enough to stick around, you could get in on the new ground floor of the community, since the game itself is loads of fun.