UT bots seem to be much simpler when you're playing CTF. I used to play the UTdemo, and my housemate and me coupled with 2 other bots could beat 4 other bots on the CTF, all of them set up at maximum difficulty(godlike bots and all sliders at max). Granted it took us 2 hours just to finish 1 god-damn 8 flag capture-limit game.
However, in regular DM I get my ass kicked by lousier bots.
Q3A bots are insanely accurate as mentioned, and also insanely quick. They tend to have a favorite weapon and always use it, even if they suck at it. For example, nightmare Klesk is one of the worst bots at the railgun, but it will always use it, even if it keeps missing. It fares much better against me with a plasma gun, but it will continue using the railgun while I kick its ass.
Also, sometimes Q3A bots get stuck in a level. I've seen bots get stuck in Q3DM7 in the grille area where you have to touch a switch for it to open. It'll just stand there doing nothing until I shoot it. Also in Q3DM11(Deva Station) it'll get stuck at the "Haste" power-up trying desperately to get to the Quad-Damage part even though there's an gate blocking the 2 rooms that's can only be open from the Quad-D side.
I play Q3A exclusively now, and its been a really long time since I've played UT, so I can't say anything else about the UT bots. These are just what I've noticed while playing.