Like many other people, since LeGuin's death, I'm revisiting some of her books.
The main character is Genly Ai, an emissary from "The Ekumen" who is visiting the planet Winter - Gethen to its natives. Gethen has no spaceflight, so he's a novelty for that. But he's also a novelty because he's a man: Gethenians have no gender for 24 days out of their 26 day month, and can go either way when they're sexually active. LeGuin uses the entire book as a platform to explore the novelty of that idea. Sure, there's a story to it, but to me it felt like it was all about the genderlessness. The result is an interesting, but fairly distant-feeling story. Not least because much of what happens revolves around "shifgrethor," a social construct about pride and prestige that she's at pains to explain is incomprehensible to normal humans (such as our eyes and ears, Genly Ai). In the end there's some explanation of why some things happened, but I didn't feel I had much of a grip on it - and the entire first half of the book relies on the concept.
LeGuin's father was an anthropologist ... which explains so much about this book.