I use Facebook and like it very much. One issue I have with it is that I am found by people I wish didn't know me. An occasional ex-girlfriend, psycho friends, and anonymous nuts should not find you so easily.
I used Facebook for my personal life, even though I add friends on it from work. I use
LinkedIn for actual work and business contacts because it's much more professional.
There are many social networking sites out there and Facebook is on the top of my list but twitter (micro blogging) is catching up -
Artemis