Stunning. I was really excited to get this book and it kept me that way right to the end. After reading her "Oryx and Crake" I was already anticipating a dystopian masterpiece but this parallel story brings the two of them into the league of modern classics.
I think anyone would benefit from reading "Oryx and Crake" first, although it's not strictly necessary, but then they wouldn't get all the resonances I did.