I've only read The Ones Who Walk From Omelas for LeGuin so I knew that I had to read up on The Dispossessed when I was looking for a space opera.

It's hard to indicate how incredible The Dispossessed is. It is a dense book with a lot of references to various political movements and ideas but its nonlinear storytelling and characterization really makes it something special. Shevek the scientist slowly morphs into a man both cynical and idealist about the future of both his people and his ideology.

What really works about these worlds is that it critiques ideas of anarchist society without letting the "old ways" of capitalism and hierarchy exhibited in A-Io. LeGuin is careful not to simply wave away problems with equality-oriented ideologies.

I also appreciate two big "little things"--the cultural hallmarks of each society were both well-defined and treated with sincerity but still unique and alien. The bald culture of A-Io with the very hairy Anaressti, the depictions of parenthood in Anaressti society. I have to say as a new father, Sheveks excitement when it comes to seeing his daughter Sadik is very emotional and made me tear up a little bit--a resounding moment of humanity in an otherwise technical and rhetorical epic of a book. 

And that's the core of the book--epic political treatise that is profoundly human.