'Controversial' is a hollow concept in the company of Scott Bakker's magnificent intellect. Most probably know him as author of the seminal "The Prince of Nothing" trilogy, which in its own way investigated one of the fundamental Pillars of Faith of fantasy literature, the anthropomorphizing of a meaningless world. In his slightly futuristic thriller, "Neuropath", Bakker goes even further; aiming the surgical light of science at the murky bogs of human self-conceptualization, perception and consciousness.
With a fairly normal thriller plot structure and progression as its vehicle, "Neuropath" stands out not because of its characters, its prose (although this is fragmentarily brilliant--uncommon in thrillers), or any feeling of absolution, but because it fundamentally challenges the reader with caustic claims as to the nature of human experience, exacted with the utmost eloquence, to the point where putting the book down to take a mental and physical breather is almost inevitable.
Along with visceral scenes of torture, sex, various traditionally negative aspects of the human condition, and the clear sense of urgency, "Neuropath" makes for a literally unforgettable read. Your limbic system isn't going to let you off the hook that easily.
This is a book for every human being, but be advised: it is a rollercoaster of one's own understanding. If you have a mind, it will be blown.