There are three groups of people in the world: those whose favorite LeGuin book is THE LEFT HAND OF DARKNESS; those whose favorite LeGuin book is THE DISPOSSESSED; and ... well, let's not waste our time on the poor fools who don't even have a favorite LeGuin book.
I'm of the Dispossessed party. It's possibly the most perfect SF novel I've ever read, and certainly one of my five all-time favorites. (The other four? C.J. Cherryh's CYTEEN, Bruce Sterling's SCHISMATRIX, William Gibson's COUNT ZERO.) But whether you like The Dispossessed or hate it - and many readers do hate it - it is the book that changed everything. And you can't call yourself a science fiction reader until you've grappled with it.
The Dispossessed is one of those sf novels, like Orwell's 1984, whose literary production values are so high that it's hard to talk about it purely as science fiction. It 's also a quiet novel, even by LeGuin's standards, and it offers pretty cold comfort to readers in search of high-tech thrills and chills. What it does offer is believable characters, unresolvable moral dilemmas, and ideas that will rattle around in your head for the rest of your life chipping away at the received orthodoxies.
Read it. If you don't like it now, put it down and try again in five years or so. Repeat as needed. Eventually this book will change your life.