The comic starts off on an interesting note where Joker implies that there is a bit of Joker in everyone and the right (or wrong) circumstances would become a sadistic killer who kills because its fun. Batman tries to understand the psychosis of Joker, to truly understand him and fails when Joker operates exactly the way he does. Its anti-climatic in the way the story progresses as it focuses mainly on Joker's origin and the way he talks calmly while attacking Barbara Gordon. 
 The ending pages has stood out for me over the years and the words are grimy and hard hitting. The way Joker's mind works is truly horrifying but doesn't mean its any less fascinating. He complements Batman in the way he thinks and executes his plans with his strategy going for a long run unlike most villains who look for short term losses. 
 Batman and Joker share a laugh. Enough said.