I found it fascinating to re-read this for book club, probably twenty years after I read it the first time.
I suggested the book because I find it appalling that more people-- and by people I mean women-- don't read good science fiction. Why is this genre ignored and other genres are not? Women devour mysteries and romance, and yet good science fiction has all the elements of fantasy that these others do. I would suspect that it is because of the hard sci-fi aspect of most examples of the genre: endless noodling about the Fardles' new gamma ray thruster and how it works, with no regard to how that fits into an actual story.
Le Guin is a rare example of all that works. First, she's a girl. Second, she can write. Third, she's smart as hell but doesn't noodle.
I had forgotten how erudite she actually is and she can sound far too academic for her fantasy audience. It's understandable-- the world of Gethen with its ambisexual/bi-sexual beings is so alien to us in terms of basic functioning, much less culture, that she needs to warm us up to the idea of it first. But by the time she has reunited her main characters-- Genly and Therem-- and even though her setting is a seemingly endless trek across a glacier, the pace feels far quicker.
The subtle discussions into feminism, sexual identity, communication and political science are left as an exercise for the reader.