I have argued for months that you should quit Facebook if you have an account. The most important reason is that Facebook not only does not respect your privacy, but in fact it goes out of its way to continue to destroy the privacy of its users.
Gizmodo offers a handy compendium of 10 reasons why you should drop Facebook like a bad habit. A sample:
10. Facebook’s Terms Of Service are completely one-sided
Let’s start with the basics. Facebook’s Terms Of Service state that not only do they own your data (section 2.1), but if you don’t keep it up to date and accurate (section 4.6), they can terminate your account (section 14). You could argue that the terms are just protecting Facebook’s interests, and are not in practice enforced, but in the context of their other activities, this defense is pretty weak. As you’ll see, there’s no reason to give them the benefit of the doubt. Essentially, they see their customers as unpaid employees for crowd-sourcing ad-targeting data.