"M" for Murder or Misunderstood?

in film class on friday, we finally finished watching "M", which is a german film about a serial child killer and how the police and criminals (ironic, i know) try to catch him.

i usually avoid black and white films because the lack of color looks dry and gloomy, but "M" isn't that bad. the first half of the movie is kind of slow and at some points confusing, but the second part is interesting.
in the movie, the murderer seems really creepy, although no one would probably give him a second look if in a crowd. he has this hunch which if seen from profile, makes him look like an ape. also, sometimes his eyes would pop really big and they give him a look of surprise and insanity. maybe he had too much sour candy when he was a kid. or maybe he didn't get any candy at all and that's why he despises kids because they had candy and he didn't.

anyway, the end of the film is a bit surprising and very impressive. it's like an inverted version of law and order: instead of the authorities prosecuting the murderer, it's the criminals who do so. and when the criminals decide to make him suffer, his reaction's so outrageous that it's hilarious. finally, he feels threatened by the mob's vicious accusations and breaks down and starts yelling and sputtering and crying and at the same time confessing of his inner demons. he looked so pitiful and miserable that i almost felt bad for him. either he has multiple personality disorder or schizo, or he's plain nuts.
which one's worse?