It's understandable why people here tend to not give a damn about Facebook. You all have more important and productive things to do with your time. However, there's a whole world of mindless young kids who join groups aimlessly, post pictures of the almost daily college parties, and find joy in spamming friends' walls.
I use Facebook, but only as a means to keep in contact with people whom I wouldn't keep in my phonebook. It serves as a nice mediator.
I think this is a sentiment of many people either actively or passively; most people have far more "friends" on Facebook than they would truly consider friends. It's more of a place for acquaintances than a place for true friends / people you keep in contact with on a regular basis.
It is for this very reason that I maintain that the "killer app" (if there is/can be one) for "web 2.0" is not going to be a social network like Facebook, but something that enhances e-mail to include these popular social network functions (or an app that uses who your correspond with via e-mail as an indication of who your actual friends are and keep you updated on _their_ affairs). My reasoning for this is the fact that, for most people, the relationships we really care about / keep up are still mostly maintained via e-mail more than anything. Sure, we can write on our friends' FB accounts or carry on twitter conversations or us IM, but how many friends do you have that you don't e-mail?
E-mail was the killer app for the web to begin with and I don't think its on the way out like many people seem to. Its still the most prolific and convenient communication method for the web.
Plus I couldn't immediately think of a non-intrusive way to collect call history from any phone so that idea was out ;-)
You can't just say millions of people enjoy it, because within that group, there are many varying segments that play varying degrees of significance in contributing to why Facebook is successful. And the mindless groups of kids who join groups aimlessly, having that show up on their news feed, and having their friends join, ultimately creating this huge domino effect of clicks, is probably what contributes the most.
I kind of share your same observation, most of my friends dont use facebook as much, but they still do, they check it like email to read all the messages, know about outings, know about new events (concerts, bdays, etc .... )
So to your observation I add, its possible that the first wave of facebook users ( i will call them the addicts ) have faded away
But now there is the second wave ... the casual users wave which is probably just as big, only different!
Finally if facebook post site usage statistics, this should be a more concrete indication of how well the site is doing
They've dealt with their (larger than Facebook) scaling issues with what appears to be industry leading uptime, they're the biggest domestic social network by about a factor of two, and they've kept up feature for feature with Facebook if they weren't already years ahead (photos, the wall, applications, etc.).
The novelty of facebook seems to have long worn off. I don't know if this is just me or a broader trend, but if I were in charge of fb, I'd look into it.