I tend to think that "extended thought exercise" is my favorite kind of sci-fi, but this book tested that assumption. There's a lot to love: the first half is fascinating, showing us the parts of our "propertarian" lives from the perspective of an anarchist outsider and rendering them absurd. I loved the notion that Pravic was essentially a conlang, built to reinforce the ideals of Annares's founding. 

But by the second half, I was weary of sociological pondering and wanted to get on with the story. Shevek was a difficult character to stick with for 350+ pages—in the same way that his (literally) alien perspective was often cutting and revelatory, it could sometimes be emotionally flat. But Le Guin tends to make slogging through the slow bits worth it with her frequent surprises of gorgeous language and piercing thought.