I'm on Facebook. I like Facebook (some days) as a way of keeping track of friends new and old. But I have also seen Facebook degenerate into ugliness. It also seems to hold the danger of replacing deep, personal involvment in the lives of others with something shallow and superficial.
Carl Trueman puts it well:
“…the church should show this generation of text and web addicts where real friendship and community lie, not with some bunch of self-created avatars on Facebook but with the person next to them in the pew on Sunday, with the person next door, with the person they can see, hear, touch and, of course, to whom they can talk, and who is created not in webworld but by the mighty Creator.”