Annihilation was weird.
I have been turning it over in my head for a while, trying to figure out how to quantify its weirdness. Was it format? Was it the narrator? Was it a combination of things?
Annihilation is a story told in a field report written by an unnamed biologist who partway through the book admits that she is extremely bad about putting crucial information into field reports. This field report is about the 12th expedition to Area X, which is a wild patch in the middle of an undisclosed location which has proven, somehow, to be scientifically interesting in the vaguest of reported ways.
People who have returned from the previous expeditions have come back wrong. They suddenly show up at home, without clearing any checkpoints and seemingly under the noses of the expedition leaders, and some of them are irrevocably changed.
This is one of those stories in which a team of people goes into uncharted territory and everything goes terribly wrong almost immediately. The suspense-building passages are tightly written, although I got a little annoyed at the biologist for choosing not to talk about pertinent plot-related details at relevant points. She does this fairly frequently -- the biologist is a stubborn, self-contained person who does not want to share any information with anyone she does not trust, and she trusts no one. I finished the story still uncertain how well I knew the biologist and whether she was withholding information from the readers. This is the first in a trilogy, so I wouldn't be surprised.
As for the structure?
The expedition team was discouraged from using their names by "them" (their corporate sponsor?), so the characters are all referred to as their job titles. The biologist. The psychologist. The archaeologist. The surveyor. However, the narrator (the biologist) has internalized this suppression of names, referring to every person she speaks about by his or her job title or relation (my father, my teacher, someone I did not know) while simultaneously assigning honorifics to non-human organisms. She names a frog, different pieces of nature she encounters in Area X, identifies specific species of animals, but she does not see the purpose in identifying people by name.
The narrator struggles with language from the beginning, either not seeming to have the words to describe what she sees or possibly forgetting that her reader might not know what she was talking about, which can make it difficult to visualize her experience. Sometimes this was irritating, other times it worked well.
Once I sat down and read this, it moved fairly quickly. However, the low page count masks an occasionally dense book that is difficult to describe. The story would probably have been more straightforward if the narrator had had a different personality. However, she wouldn't have been nearly as interesting had she done what she was supposed to do in reporting the facts clearly. In exploring them as she saw them, the narrative swiveled every time circumstances or context required her to unclench her grip on information she seemed annoyed to have to share.