Most of my friends/family live in other states or abroad so FB is a great way to keep in touch with them and "share" quick experiences and photo's. I was very skeptical at first though, reading stories about people (mostly dumb people) who got fired, denied a job, or found by police because of FB postings. At the time I joined I was laid off and job hunting. So I joined under a different name. When I sent friend requests to family/friends I sent the request telling them who I really was so they wouldn't think I was a weirdo (well I am, but they still friended me).
I'm not terribly into it, I don't post a lot. Although one late afternoon my husband, myself, and his three kids in England were posting back-and-forth rapidly and we quickly had a "threat" with 150+ posts! It was a hoot then he finally told them to go to bed!!
We're able to see our first grandchild grow up in FB. We were able to be there when she was born, but we can't fly there as often as we would like. She's 9 months old now and took her first steps last week :)