Colson Whitehead's latest book, "Cool Machine", is being reviewed as the final part of his Harlem trilogy. The novel is described as a crime caper set in 1980s New York, with some outlets praising it as a fitting end to the trilogy and a potential classic of New York fiction. Reviews characterize the book as freewheeling, gritty, and fun, with some considering it a strong contender for book of the year.