I LOVE FB. I have connected with friends from 30 years ago and love hearing what is going on in their lives. I like feeling connected to people who live far away from me. I like learning about new things from my friends, I like communicating and laughing with my friends. I am careful who to friend. If you are not my friend in real life, I am not inclined to friend you. I am not friends with my friend's children, nor friends of friends. If I don't trust you or don't know you well enough to trust you I will not be your friend on FB. I am not likely to friend anyone I do business with because I tend to keep my professional life separate from my social life.
I wonder if people's bad experiences with FB tend to be the result of friending the wrong people. These wrong people may post things that some consider inappropriate and it is then easy to blame FB and not the person (people) who are saying or posting ugly, rude or otherwise inappropriate things.
I think that like anything, you can overuse it and it can become a place that is not healthy. It depends on how people use it...not on the technology or concept.