Facebook is not for me. Msybe its because most of mine freinds are party people. I feel very isolated. I rarely go on it and I find github the only social network I really care about. I feel as though its not really that social though since I only get to talk to people when I bring something to eat the table. Big node repos +1s, the I barely use the follow feature despite having access to some of the most prolific programmers of my time. I want a social programming network. No idea what it looks like, but github has definitely helped curb the isolated feeling. I havent played around with gitlab enough but Im sure it has more potential
In that respect, if you're looking for a social network to keep in contact with a general group of people, Facebook is the way to go, and not the myriad of smaller sized social networks. If you're only looking for communication with a small group of people who haven't committed to anything, then you could jump ship to Google+ or whatever. Size of community is the salient feature, not the app.