I still don’t get Facebook – despite being on it. If I want to talk to someone I will call them, email them, text them, meet them, have dinner with them – get the picture?
I am quite worried about the security and privacy elements of it – or rather the lack of it. Those who know me well (anyone?) 
know I was not always this paranoid but after attending a few Security courses – I cannot bury my head in the sand anymore.
The main issue I have is the commercialisation of the information and it will just get more as Facebook heads to compete with Google – it is my information after all and I don’t feel comfortable sharing so much of it – even after locking it down and setting the various privacy settings. It is very easy to exploit. Take the example where Facebook changed the settings where Google by default would be indexing a lot of this information. And it is you and I as users who had to login and explicitly change a setting to stop it from doing that. Furthermore, despite all the security measures that Facebook might have in place (and they don’t mention how internally within the company walls is the information protected) all it takes is one disgruntled employee (or soon-to-be-ex-employee) to take it all and walk out the door!
The secondary issue I have is the fact that more and more of the information, friends, contacts, etc is marketing and spam (a lot of what we see on Twitter as well). I personally am (thankfully) seeing much less spam on emails these days; but on the flip side I see a dramatic uptick of spam on social site. Not sure if this is because our email spam filters are finally smart enough to work, or perhaps the spammers found the social networking sites to be richer pickings?
It is good to know that there are others out there with the same concern and with some sites such as Suicide Machine allow you to “all your energy sucking social-networking profiles, kill your fake virtual friends, and completely do away with your Web2.0 alterego” [sic]. Of course, all has not been peachy for Suicide Machine at the same time.
If you are thinking like me and really giving it a go then suggest you seek some help as well to make it easier.
The irony of all of this however is that I will be posting this it to my Facebook wall and also tweeting it.