There used to be a sign at a bar in Austin that read "Everything in excess. Moderation is for monks." Back in those days, we all made the effort to comply.
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 .