It's a tool, it largely depends on how it's used. It's more of a personal question than one that is best answered by statistics. What you should worry about is

It's a tool, it largely depends on how it's used. It's more of a personal question than one that is best answered by statistics. What you should worry about is whether it increases / decreases your social interactions and how social you want to be. Perhaps you want to be less social and Facebook enables that, perhaps you want to be more social and Facebook also enables that. It really comes down to how you use it. I don't think I've ever thought 'I'd really rather not go out tonight, I'll just find out what happened on Facebook tomorrow.' For myself I find out about events that I may not have heard of because I didn't speak to that friend that week. I think Facebook is neutral for good friends and increases interaction with friends at the edge of your social circle. It's also a great place to keep in touch with people that you only see at certain conferences, events, etc. It's essential for me for keeping in touch with campmates from Burning Man.