Once you indicate your less than favorable reaction, a thumbs down icon will appear under the post that ostentatiously calls out your dislike, with your name attached, for your Facebook friends to see
Excerpt from Mashable.The cons: You need to install a firefox plugin, which I assume that non-firefox user won’t be able to do this, to perform the dislike. You also need the same plugin to see the thumb down of dislike.
Oh, is there any way to completely dislike the facebook? My only problem to Facebook is that the content fully centralized on person, not information. In a world where informations is the center of universe, Facebook is heading towards the opposite direction. Unless if Facebook believes that narcissism is the most valuable information to expose.