I think the main issue with Facebook, or at least mine personally, is that when I started using Facebook a few years ago, I made myself completely private. I was invisible in searches, friend lists, everything. Unless I added you as a friend, you had no idea that I had a Facebook profile. The only reason I really had a Facebook profile was to keep in touch with close friends who've moved cross country or overseas, so this worked well for me.
Then what happened? Random privacy "update" from Facebook! Now all of my privacy settings are reset to default, and because I don't use the service as often as most, it goes unnoticed for a few days. Then the friend invites start rolling in. Then harassing messages from people I didn't want contact from (another reason I was private). So I set it all back to normal and went about my life.
Oh, but then another privacy "update" from Facebook! This time, not only do all of my settings go back to default, but they've also removed the ability to be invisible in searches and friends lists! Excellent!
Fuck Facebook. Seriously. I get why people like it, I get why people use it, but for people who really do value their privacy (me) and want to use the service, we'll forever be screwed by their ever changing garbage "updates" and changes without prior notice.
This is the main reason I'm excited about Google+. If they can solve those issues then I'll sign up in a heartbeat, convince the people I use Facebook to communicate with to make the switch as well (or at least get a Google+ profile).