Meh, one could argue for or against the dern thing. Like anything, it depends how you use it.
There are friends that insist that it's a great way to keep in touch with people from home/high school, and I believe it (from them). Ideologically, it's not at all a flawed site.
The flaws come in with how most people use it, spending hours facebook-stalking other people, organizing the most ridiculously stupid moments of their lives into albums to flaunt in other peoples' faces... All-in-all I love the site because it proves that everyone is just as pathetic as everyone else, and we all feel the need to prove that they have friends, to over-compensate for our lonely condition. =)
Oh sad sad world... It's for those exact reasons that I don't support the site, at the same time. Forget how we all feel in the here and now, we can be sure that the state of our world and our society today is the result of all the preceding actions enacted by our predecessors. In such a way, what we do now will, of course, affect future generations. So if this big old snowball called facebook is allowed to keep rolling indefinitely, who knows how big it could get? Big enough to swallow up the totality of everyone's interactions. And if that happens... well we can rest assured that this will be far from the only forum of its kind anymore. =P
But anyway, take pride in not having one. I do. =) Thoreau would give me a big, friendly pat on the back for it.