I've heard about it, but I'm not much of a moviegoer, and the word "social" tends to bring the anti-social out of me. That said, it does look nice, maybe I'll create an account later just to try it out.
The social aspect is such a minor function of the website. The social aspect boils down to find people who have good taste, or similar taste to you, or who analyze movies in a thoughtful way so you can see what they watch/like/review and get ideas for what youd like through that. You dont even have to use those functions though. I mostly just use it to keep track of what movies I've watched and find new movies and make watchlists.
Honestly there's not a lot of people on the website, so you could completely ignore the social aspect and it's still pretty useful for logging the films you watch, etc.