Facebook is questionable at best, but at the same time so widely used that sometimes people may feel disconnected from others if they're not on it.
The truth about Facebook is that not many people really have anything interesting to say. This isn't really a knock on people, but more so a reference to the fact that it sort of just becomes a thing you look at, and update almost because you internally train yourself to do so. You're going to likely see a lot of people simply posting messages such as "I went to the mall today!" or photos of their lunch.
If you're going into Facebook expecting to become closer to friends you already have, I would argue it isn't going to be very likely. However, it can be effective for meeting new people at times. However, it's effective in the same capacity that this forum would be - joining social groups on a specific topic, and just talking about it with people.
There isn't really any downside to having an account, so it may be worth making one to try it out. What you get out of social networks mostly depends on your own personal experience and what you use it for. My only real advice is if you do make one avoid complaining about your job, as some workplaces have a habit of looking up that stuff. I know somebody who got fired over Facebook comments. Don't post anything you wouldn't want the person you're speaking about seeing, essentially.
Twitter is a bit more popular at the moment, and potentially easier to keep track of for the record.
