I read The Collector a few years ago. It's hard to verbalize, I read it, it propelled me along and I couldn't stop reading it, but I could never say that I "enjoyed" it. The protagonist, is awful, does awful things, but what is more uncomfortable is that you are put in his head for 75% of the novel. It is a horrible place to be, and you can't easily separate yourself from him. You are seeing his thought process and hearing his innermost desires and goals. And those desires and goals are so contrary to normal human life and decency.

Pair that with the portion of the novel that switches to the Miranda's perspective and seeing the events of the novel through her viewpoint. It just makes it so much worse to have to go through her suffering with her, but also to have been with her captor as he executed his plans. It is interesting that in most ways, both people agree on the particulars of the events, what they did, etc. It's not that one party is lying and the other is revealed to be being more truthful. There isn't some grand twist that grants greater understanding. This man does this shitty thing to this woman. That's it. And he will keep doing it.

I know there are deeper interpretations, which I haven't really delved that much into. For me it was a rough read.