I use FB but never, ever the app
Yes, I use FB to stay in contact with fellow photographers, set meet ups and discuss photography related points and posts pics but the second I pulled up the app from the store and saw that it wanted everything from my phone, that was a step too far and never installed it. I knew what I signed up to FB for, I knew they'd own whatever gave them but I want to at least have some minor control over how much they know about me or can deduce from me. The app leaves no stone unturned and once they have whatever you give them, there's no taking it back.