like the majority of horror stories, let me in is a discussion of what makes a monster. is an alcoholic dad more terrifying than the vampire next door? the juxtaposition of good and evil is played out in almost every character interaction and none of the characters are all good or all evil. There are big evil things like rape, and then there are small evil things like not sharing your deceased parents stamp collection with your sibling. For this, this story has a certain realism.
BUT:
be warned!!....there is a great deal more violence in this book than there was in the movie. and i'm not talking about just blood and guts. there is a whole lot of emotional violence, and an equal amount of sexual violence. the inner monologues of lindqvist's significantly better developed characters stomps right over the line that divides unsettling and downright disturbing. Having said that, I will also say that little if any of said violence is gratuitous, it makes sense in the context provided.

it's a good read if you like that kind of thing.