they mainly use it to show their photos to their friends.
Me? I'm not a huge fan, I have plenty of other ways to keep in touch with the people I know. That doesn't mean I disapprove of the concept, I just don't think it's been perfected yet. I'm concerned about the 'closed world' aspect of something like Facebook, or any other social networking site that aims to be all things to all people.
Like Tim Berners Lee I think the Internet is in danger of becoming a series of virtual walled cities, run by large organisations which want to offer users a 'cradle to grave' experience, so they won't feel the need to venture further into the vast open spaces that exist beyond the city gates.