I have no Mouth But I Must Scream by Harlan Ellison
One of the primary reasons I love to read is to see the world from a different perspective. A book can bring us closer to the mind of someone than any other media. A well-written story is the closest thing humans have to telepathy. Which is why "I have no mouth but I must scream," is so frustrating as a story.
"I have no Mouth but I Must Scream," by Harlan Ellison is a well-written story I would define as horror rather than science fiction. It is also one of my least favorite stories of all time. It is mean, angry and pointless except in so much as the hopelessness is the point.
If you haven't read "I have No Mouth but I must Scream" this is the point where I spoil it. Not that there is a lot to spoil. The story is made up almost entirely of two things, atmosphere and torturing the main characters. The basic premise is that during the third world war humans created an AI which gained sentience and killed everyone except the five characters in the story which it horribly mutilates and tortures through the entire story. Eventually the main character breaks and kills everyone else. It then changes him so he can't kill himself and kept alive forever for the AI to torture.
That is the entire story. Everyone is dead except one person who is tortured forever. No real plot, not much character development and no hope. This won a Hugo. And it probably deserved it. It's written better than man far more enjoyable stories and I'm sure if I could bring myself to wallow in it longer I could find more to admire in the way it was written, but it does its job too well and makes me miserable when I read it.
I have often said any story that makes me feel anything is a success. The only real way to fail writing a story is for it to be boring. But just because a story succeeds doesn't mean I have to enjoy it. In the case of "I have no mouth but I must scream" it certainly makes me feel something. But I can't recommend it to anyone, unless you enjoy hopelessness and want to be miserable for the next few hours.
PS: Mr. Ellison passed away a short while ago which is what drew me back to his work. I can't say I love his writing, though it's always good, but I've heard a ton of great stories about the man. He was tough, gruff and from everything I have heard one of the kindest people to have ever put pen to paper. I wish I could have met him.