Years ago I read "Carrion Comfort" by Dan Simmons and thought that he was rather overated as an author. Years later I read his science fiction novels, Olympos, Hyperion, Endymion and saw what I had missed in the earlier novel. He had the workings of being the greateast novelist of our time. "Black Hills" however, was rather dull, "Drood" absolutely wondeful, "The Terror" also. This novel is good, Mr Simmons playing with American History just as Neal Stephenson did but Mr Simmons does it better. His Sherlock Holes is as enigmatic as the original; strange, distant and far too much the aesthete for the normal person to fully understand. Henry James, an awkward person in real life becomes the comfortable norm in this tale. Mr Simmons adds to the mix, the question wither the estimable "Holmes" is truly real and not just a fictional character, doubling the mix with the possibilty that the fictional holmes is conducting an investigation in the melancholic "Mr James" mind.
This will never be viewed as Dan Simmons best book. He has written some of the best books that I have ever read. But most will love this as he is a better writer by a country mile, in a bad book than most writers (and I include myself in that category) in a great book. This may not be his best but it is still better than most authors will ever write.