I also hate the tagging.
For instance you do not usually opt-in to a group by yourself. Instead somebody else includes you in that group, without your permission. This is bad because opt-out of a group is an explicit statement that you don't want to be in that group, versus just ignoring a request which could just say that you don't have the time for that or you missed the invitation ... and people know you in those groups and opting-out is just rude.
This is not how real-life works btw.
I also got tagged several times in pictures that I do not like. Those pictures automatically appeared right on my "enhanced" profile page. When I untagged myself the person that did it thought it was some kind of technical problem and tagged me again. Then I untagged myself again, and got tagged again. Then I told that person that I don't like that picture and she got upset. I don't want other people tagging me - I want to tag myself in pictures that I approve of and this is something that Facebook won't allow me to do.
And talk about automatic tagging -- fortunately Facebook allows me to deactivate automatic tagging (for now), but this feature is just plain evil IMHO, as it encourages people to tag other people, even though that's not something they really want to do.
This list could go on and on and yet Facebook provides no means for me to automatically download the contact details of my friends. How fucked up is that? These are my friends, and many of them I invited to Facebook myself.
Basically these days I'm only using Facebook when I want to get in touch with somebody and I have no other way at my disposal OR if I want to spam people I don't care about ... but the real social networking that I'm doing these days is through my phone or through my email address.