I had it for a while, and between work, friends, family, friends of friends, friends of family, music contacts, dating, etc., there was absolutely NO way I could keep up with it, and when you can't keep up with it, people get offended.
Since then I was urged repeatedly by people here at CB to get it again, so I used my screen name, hoping that way it would just be people from here, and I could keep up. I was wrong, and I think I'll need to close it again. I completely see the value in it, and it's a great tool, but I honestly just don't have the time it requires, and I'm trying to become less social, not more.
I have also found that for purposes of the music industry, (at least for me), MySpace has become my preferred tool. For some reason MySpace is HUGE with people in the music and entertainment industry, and it has been priceless for me in that respect.