I dont do Facebook and have never responded to the requests I sometimes get out of the blue to join other sites like Linkedin or Badoo. I dont Twitter. BUt I did join Circalit - a site aimed at supporting screenwriters of all levels, but only to enter a short story competition. I put in a piece of creative non fiction - Return to the House of Tango- which is basically about how I started writing. Talk about baptism by fire...I was ganged up upon by a couple of diehard members who accused me of making up my own reviews! For a while I felt quite upset by this. Then out of the woodwork came my supporters and the sand bagging ratings these die hards gave my piece were removed after I and my supporters complained to the site administrator.
I think Circalit does a great job in promoting networking, peer reveiwing and supporting screenwriters and clearly has a strong following but with openning out into other genres they seems to have created a stir within.
The experience has confirmed all my personal gut feelings about belonging to social networking sites - instant friendships, instant on line peer reviews, instant everything! One hears about people being bullied on sites- I think it must be a terrible thing to go through.
Have already meet some nice and interesting new writers aswell though so I suppose its swings and roundabouts- but I wont be joining anything else just yet. I also value my privacy too much.