I think it's quite good. I can play Risk with my high school buddies again. I can come into contact with ignorant fools refusing to have functioning blogs, phones, msn, icq, aim or skype. I can easily click the option to ignore all requests and invitations from all the morons I never speak to. It's just another tool for communication, one geared toward students. Now what about the downsides?
1) Reconnecting to people I didn't stay connected with. If I wanted to be your friend, I would not have ignored you for the better part of a decade.
2) Connecting to people I barely know. I don't know you and I have no interest in knowing you.
3) Poke someone else... please. If you want to say something, just message me! What? Too lazy to do that? Then poke yourself in your eye.
4) Friends who don't keep in touch but update their profile. Your social network is not a blog. Keep in touch. Seriously.
These answers aren't directed specificly to you ptgatsby, I just thought you summed up the common critisism in a good way.
1) So what, just ignore em. However, if youre not there to use it as a communication tool, I can't see what you would do there at all. And if you're there for a reason I can't see why you would deny the opportunity to build a network, after all: they do it for you and you don't have to give them any info or time (more than the accept-click).
2) Well, why would you have to? But if you actually are in the process of getting to know them you can use facebook as a tool to further your evil plans.
3) Yeah. But they can easily be ignored. There is a function for ignoring them.
4) Don't see it as your social network. See it as any old network. And utilize it.