I saw an article somewhere that suggested that facebook is no longer cool. they said it had become uncool.
I think it all has to do with real time/instant time response. for that reason twitter and some of the other emerging social media innovations are capturing market share from facebook.
Both FB and Twitter are too real time for me. I don't like the disappearing posts thing.
FB also doesn't keep stuff on your timeline for a decent amount of time. I like posting, reflecting on posts, and sometimes going back and adding new insights to previous posts.
That's why Camelot works for me.