The book's themes fit squarely inside this nation's continued conversation about race and our racial struggles. You could see it merely as a rumination of how we would now be living our lives if Lincoln had been shot earlier than he was. No, there's nothing wrong with a Gedankenexperiment, in general. But I can't imagine that this book isn't in some way a slap in the face to African Americans. In other words, Winters is showing a world that would be far worse than the racial dynamic we currently have. How can we not interpret that - at least to some degree - as essentially saying "well, it could be worse! maybe you're not so badly off?".
On the face of it, this is a stellar thriller - it rolls right along, has a zillion twists and turns, and you both engage with and root for all the characters, not just the main one. (Even when you lose sympathy for our main character because of his truly abysmal past choices.) I can see there's even a sequel to this, based on the last chapter. I just find it difficult to understand how his editors and publishers let this one out the door without at least a side note on WHY Winters crafted this tale. I've read no other critical reviews of the book, but I would venture to guess I'm not the only one that finished it with a nasty aftertaste in my mouth.