As I've said before, I'm no fan of Facebook - in fact, I think that ultimately, it is no more than a poor caricature of what social networking can be and do. Clearly, that's not stopped the site's rapid growth, but as Facebook users themselves have had more time to come to terms with the environment they're now operating in, I think it's in good part responsible for the fact that in some key territories, Facebook usage numbers have now plateaued and even declined.
The main problem here is with the thoughtlessness with which Facebook handles what should be its central asset - the social networks that its users belong to. Social networks are defined in the first place by the term 'friend', but being friends with someone on the site is no more than a binary decision: you either are, or you're not. There's no opportunity to do what we do in our lives outside of Facebook every day - to distinguish between different types and levels of friendship: work colleagues, old school friends, family members, neighbours, ex-lovers, casual acquaintances must all be classified simply as either 'friend' or 'non-friend'. What's the use of that?
On my Facebook profile page (which I hardly ever visit), there are now some 30 friend requests waiting for me - some are genuine friends, some are students and colleagues, some are casual acquaintances or friends-of-a-friend. Overall, they have nothing more in common than that they - somehow - know (of) me. In no context other than within the artificial sociality of Facebook would anyone consider all of these people to belong to the same category. And I have no means to properly qualify the level of friendship which connects me to another person - I can't distinguish between people I've known for 20 years and people whom I've never heard of, but who may have read one of my books; I can't tell family members from colleagues at work whom I occasionally exchange ideas with.
This fundamentally ignores some of the basics of how we as humans understand the social networks we're embedded in. We don't just see everyone as our 'friends', but instead have social ties with others that are more or less strong - and for most of us, there's a pretty low upper limit on the maximum number of really close friends we have. (Perhaps it's just me, but I don't know that I'd even say that I have 30 extremely close, 'through-thick-and-thin' friends - so who are those 30 who want to befriend me on Facebook?) Which highlights the absurdity of the Facebook 'friends' system: any social network that enables any of its members to claim that they have 10,000 or more friends doesn't deserve to be called 'social network'; what the tag 'friend' in Facebook really means is no more than 'here's someone I know (of)' - and what good is that if I can't also say 'but here are my very best mates'?