Not that I'm at all biased, but one of the best dystopian novels of all time - often considered the fourth and final great literary dystopia of the twentieth century, closing the arc that begins with Zamyatin's We (reviewed for us by James), and continues through Huxley's Brave New World and Orwell's Nineteen Eighty-Four. That the book is mentioned in the context of those names is really enough of a testament to its quality.