Chapters I-V were interesting enough, although chapter V was a bit slow for me.
But I just finished Chapter VI ("The Abyss Gazes Also") and it just blew my mind. Rorschach finally explains how and why he became Rorschach. It was horrible, sad and so powerful. I stopped reading because I need to take in what I've just seen. Kudos to Alan Moore for being able to pass all those emotions from the paper to the reader.