I use it - mainly when I started to catch up with people I'd not seen in years, but more now for Greyhound Rescue related stuff, and crafting. The Marketplace is handy for buying stuff as cheaper than e-bay (free to sell too). I'm not like many who live their life through it though - it's far to public for me
I use it every day to make connections and promote my books. I post in Facebook parties when I have a new release. I have met some interesting people online who I meet now in real-life and are friends. There are a lot of men who are lonely and try to make friends. Beware! I block them as some them are peculiar although others are just military guys who are lonely.
I am not a fan, my sister however posts her whole life on it .... probably why I am not keen .... she is trying to promote herself and her business but it just gets on my nerves. My kids rarely use it these days (they were the whole reason I went on it in the first place, to see what they were posting), they say it's for middle aged people (they prefer Instagram ... whatever that is!).
I'm also not on Twitter or Linked In .... I really don't want people from my dim & distant past to be able to look up what I'm doing now, I value my privacy.
I set it up then cancelled it but then was persuaded by a friend to reopen. It was fun at first as I used to organise a lot of school reunions so could share photos but not everyone was on it. Now I find there are maybe 5 friends who post regularly and I feel guilty if I don’t ‘like’ their posts so I never post or like. It is useful for looking at updates for my area, the police, particularly traffic problems, local area with local goings on like door knockers about or recommendations for local services. There are lots sponsored adverts which annoys me. I hope the owner, Zuckerberg makes good use of his $50 plus billions!