No question that you'll want some more recent insights; but, a quick search of the site yielded the following forum discussion. If nothing else, it might provide some helpful background information.
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 .