A terrific book, although I expected no less from Mr. Martin. As usual, his characterizations are superb, his action is gory and vivid, his details are well researched, and his meals are tasty-sounding. If there is a major flaw with this novel it's that it's too short (kidding, kidding!).
If you've been become enamoured with the more recent depictions of vampires in popular fiction, then this book is not for you. It worked quite well for me, however, as I firmly believe that vampires should be horrific, not sexy. Fevre Dream does for the vampire what Robin Hobb's Rain Wilds Chronicles did for the dragon; it provides a sensible ecology within which vampires actually make sense, completely doing away with all the religious nonsense which traditionally surrounds the mythos of Nosferatu. The vampire is typically portrayed in a manner which presumes the existence of the Christian God, whereas Martin here redesigns and transmogrifies the vampire into a ferocious and believable predator whose favourite food is homo sapiens. Having re-imagined the nature of the vampire Martin then asks, "What would vampires do in the antebellum era of the United States?" The answer seems fairly obvious - they would be slave-owners, of course, and Martin explores this with typical candour and brutality while also not failing to draw the comparison between vampirism and 19th century America's parasitic relationship with its slaves.
This book has a lot of selling points and no glaring weaknesses. It seamlessly blends fantasy, horror, and historical fiction. The narrative voice changes depending on whose perspective is being followed. Steamboat technology is portrayed in as in-depth a manner as is necessary to make the reader believe that Abner Marsh is a competent steamboat captain, while never bogging down the story. Marsh himself actually changes as a character, although not in an unrealistic way. All things told, this book should really be more well-known than it is.