To me the thing about JY is that they lay it on really thick about how "evil" he is, but he rarely actually does anything. Mainly he just sounds "evil" with his voice.
Recently I listened to the original story of Jeckyl and Hyde, and it wasn't much different. At one point Hyde beats someone to death, and we don't find out if he had a reason or what it was. For the entire rest of the story, we're told over and over that he's engaged in all the worst sorts of depravity, without one word given as to what that consisted of.
By the way, Hyde was a very small man, and it seemed as if he might be Jeckyl's or RL Stephenson's sense of an inner, repressed, misbehaving, naughty little boy. He came across as a sort of out-of-control monkey.