Full confession: I have a Facebook.
But I really really hate Facebook. It's not so much the principle of the site that I hate, so much as certain things with the way it's implemented.
First, I hate certain privacy settings. They recently changed the way to choose your settings, which is nice because it gives you more options. But certain defaults are not palatable. There is no way to hide who your friends are and what pages you've become fans of from anyone searching you - and advertisers. And certain details, like 'website', were automatically set to be viewable by everyone - you have to change it to prevent that. You also have to change a setting to prevent your information and profile photo being used in ads aimed at your friends.
Second, the design is clunky. The news feed is a very limited (too limited) feed, and the live feed is the exact opposite - an electronic diarhhea of every single things your friends do. I don't want to see what groups they join, what applications they use, or what they say wall-to-wall. All I want to see is what statuses they post, and maybe when they post pictures or whatever. I liked the old design - a single page that showed all your friends (by last name, not first), their most recent status, and whether they'd updated their profile recently. Simpler and better. Less like #$%$^ing twitter.
Third, the programming is clearly a kludge. It takes forever to load, and often there's timing problems with the feeds - they'll repeat after 25 posts, or only show a few with no way to expand the feed. Bloody annoying.
That said, Facebook can be very useful. I use it to get updates from Madcow and Aerotech, and it's useful for communicating with my friends. It's also useful for keeping in touch with relatives and friends that you don't see much. Even though when you do talk to them, it's often bad, like tonight. I learned from a friend that a guy I knew, who I was on the CT state ARML team with, passed away today in a bus accident. Great guy - ridiculously smart. Made me look like a fool when he got to working on a difficult problem. Vikas Parikh, we won't forget you.