I've been on Facebook for several months now and I have to say it is both addicting and annoying. Clearly, they have created a social networking site that works. This is what friendster always wanted to be. The web-design is very clean and appealing (as opposed to blinky, flashy and cluttered) and they cleverly got in on the ground floor with college frosh nationwide. Then they let the oldsters like me in the door. And as a way of finding and re-connecting with old friends, it's effective if only due to its vast size. So ... w00t for them.
As many have pointed out, Facebook is also evil (or potentially evil), with connections to the CIA's venture capital firm, the DOD and the founder of (shudder) the Stanford Review. That's not to say Facebook is necessarily doing anything vastly more evil than Google (i.e. corporate data-mining and targetted ads), but if anyone in government ever gets the bright idea of re-starting the Total Information Awareness system, I guess they know who to talk to.
But really, my main gripe with Facebook is all the requests. In the 90s we all got chain letters asking us to Save Sesame Street or forwards brimming with inspirational sayings -- now I'm being asked to turn my friends to zombies or forward FunWall posts or take quizes on how many kids I'll eventually have. The big improvement seems to be that the chain letter now installs itself on your profile page and automatically selects a list of friends to forward on to. Really? No thanks. Maybe I'm just being grumpy, but with Facebook there is an exhausting expectation that you're supposed to communicate through an endless volley of thrown sheep.
Don't get me wrong - some of the apps are pretty cool. The Wall is nice, and SuperPoke is cute. I love the maps and the webcomic feeds and its nice that they've resurrected Oregon Trail. The open source development of applications is clearly the way to go and I'm sure there are some very creative people writing some cool and useful programs out there. But I don't think it's quite the killer app that will help grow a true online community - there's too much noise right now.
Of course, I still want you to be my friend...