When asked in a private interview what he thought of his customers providing Facebook with all their private information, Mr. Zuckerberg referred to his customers as, "...a bunch of dumb f**ks." At that moment I lost all respect for that simple twit.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .