A review by explikator
The Left Hand of Darkness by Ursula K. Le Guin

adventurous emotional inspiring mysterious reflective medium-paced
  • Plot- or character-driven? Plot
  • Strong character development? Yes
  • Loveable characters? Yes
  • Diverse cast of characters? Yes
  • Flaws of characters a main focus? No

5.0

 "The king is pregnant". This book must have been like a revolution for Science Fiction, back when it was published in 1969. It's not "hard" sci fi at all, its concept is a thought experiment. What if there was an androgynous human race on another planet, where everyone is not a he or a she, but both? What if they develop libido only on three days a month?
This is the topic which made "The Left Hand of Darkness" so famous in its time. Now, fifty years later, where we discuss gender on a new level, its conclusions have not lost their appeal. One critic on this work was, back in 1969, that the protagonist labels everyone he meets as "he", even though "she" would have been sufficient, too. That's a good point, I guess. But 1969 was before the second wave of feminism and the heroes in science fiction still were mostly manly men. Other books published that year were "2001: A Space Odyssey", "The Man in High Castle", Slaughterhouse Five" ans "A Clockwork Orange" - no female characters with their own agency in these, yet they are called classics.

Soft spoiler:
I was even more fascinated by the religion that had developed in Karhide and by the love story between the Terran named Ai Genry and Estraven. Their love was only possible because they were different. It's not a deep understanding of each other or a sexual tension binding them together, but the respect of the fact, that each one of them is an alien to the other.