I'm puzzled by the various contributors to this thread who seem to think that FB is somehow instead of phone calls and meetings. It isn't, for me. It's as well as. And it's far easier to keep my friends in touch with what's happening for me through FB than making loads of phone calls - far less disruptive to their lives, too, as they can choose to read the short updates or not and whether to respond or not. I still have a real social life and FB adds to this, rather than detracts from or replaces it.
Through FB I have been able to follow my nephew's year abroad (sometimes in rather too much detail, perhaps, but it's nearly always entertaining) and re-made contact with friends I had otherwise almost lost touch with.
What's not to like? Yes, you need to be adult about security issues and which apps to follow or not, but otherwise it's all good fun. I'm even able to play games of Scrabble with some fellow performers who I would otherwise only see in the occasiona festival green room.