And WTF, it gets you packet loss LOL. Seriously, even if you were to implement microphone settings and controls, when I was in a server that had at least 3 of us using mics, all I could hear was either really quiet complete sentences, or horribly broken up and stuttering audio from someone else. Wish there was some Vent/TS servers now for the servers I frequent, namely Racquemis'.
Most of the heavy lifting with regards to voice is handle by Steam itself, so we don't have complete control over it, or even enough control to do things like tune mic settings. You can do that in Steam under settings->voice. However, if you can be a little more detailed about exactly what kinds of awful behavior you're seeing, we may be able to improve things. We already have some better UI stuff in the works so you know who/when is talking. Beyond that what sort of specific problems do you encounter?
I thought it was using the built in UT voice features since it was tied to Stat Net, but even then I really wouldn't recommend using Steam's voice system, since it's actually quite crap. Whether it be using the Steam Overlay voice or L4D's lobby voice chat, you tend to get an awful lot of feedback, poor quality audio or even total lack of response from push-to-talk/constant background noise on mic activated. In-game in those games it uses the source engine to handle voice chat, which is why it sounds so much clearer and nicer, but I don't believe that might be a valid alternative you could use sadly. If you decide to continue using Steam for voice chat I could see most people would be unable to find the microphone settings without being directly talked to and therefore it would be rendered moot if you don't add a feature that partially mutes the game sound whenever someone opens their mic, since MICKEY CANTOR HEYOOOO will ruin ANY kind of attempt at verbal communication most of the time. Of course, it would also help when you get that UI feature implemented so people can realise HEY I'M TALKING TO YOU! NO THAT'S NOT THE TV, IT'S ME, because then it seems likely it would get everyone else using the mics more often, so we can have more mics to test and figure out if it's anyone in particular who has a problem or the speech codecs.
It largely depends on the player's own settings and their microphone. I have played with plenty of people that know how to set up their microphone properly and have had no issues with hearing them clearly. There will always be players with terrible sounding microphones, including voice chat programs like TS, Mumble, and Ventrilo. One weird thing though, I had to rebind my Talk key to get it to work. I kept it the same, t, but it never worked prior to going into the settings and going through the rebind process. One of the recent updates may have also been the reason it suddenly started working, but that's what I did on my end.