I'm on there but I never use it. I did have some woman try to get me to add her to my links. Didn't know her and all the info she had was the term "barister", which I know is a "Lawyer" in the UK. So I just ignore it.
I get lots of requests from various IT persons in India.
That in itself sounds suspicious.
Some of them are.
About half of the relatively serious ones see me as a potential customer. They want to sell me their services (document conversion, proofs, etc). There are a few who are legit, though, and in the same field as I am.
LinkedIn is the grown-up's Facebook.