"The story of a boy becoming a man." Or "The story of a slave becoming a freeman." Or "The story of a man traveling across its country."
All those could serve as a quick description of the story. And all of them would be, at least, a bit wrong.
Because it's not just one of those. It's all of those. And a bit more.
At first, I was quite disappointed 'cause the "Powers" at the title are mentioned very early and then... nothing. There is a lot of going back and forth (a few transitions are a bit weird, like suddenly the story being a letter to the protagonist's wife) and you keep thinking "Were the heck is this going on?" And then, suddenly, you keep reading a bit more because you want to see a thread closed, and then read more, and more, and more... It's quite the same feeling I got from Changing Planes, although the story here is way more complex (not quite hard, as Changing Planes is a bunch of separate stories instead of the continuous story of a slave who runs away, make friends, finds his people, in a span of 10 or so years).
One of the things that Le Guin impresses me is how the way she describes things approaches the way Isaac Asimov does: Describes the very minimum necessary for the reader to understand why the characters are doing something, and let their imagination soar with the rest. It's quite different from Arthur C Clarke, which likes to over describe stuff.
In the end, it was a story that I was mostly uninterested at first but that deeply moved me in the very end.