I am in no position to rate this book. But still I'll try to give you some of my thoughts.
The way the author keeps all dialogues not separated from the narration (same line, without quote, only to be signaled by uppercase) at first bothers me a lot (even though I did read one or two books written in this way, Blood Red Road for example). Still it's only with this book that the effect becomes so profound. The story flows nicely. To add to this, each paragraph is normally one and a half page long, and there is no chapter at all - which I have to take a lot of effort to concentrate, not to lose track of what I read. The result is that the book is given a sense of endlessness, and the same time an unmatched intensity. I keep shouting in my head "Give me a break, please, this is too much, I need to take a breath." But no, I'm not allowed to do so.
The plot is very difficult to give an opinion. It is a kind of an allegory, and the extent to which readers can make sense of it is not for me to tell. The idea of blindness, specifically white blindness, itself already triggers some important thoughts. And then there come the issues of human organizations, of moral and dignity, of life and hope.