Very effectively creepy.  Reminds me a lot of an Aidan Quinn/Kate Beckinsale movie, Haunted, and John Gielgud, in which everyone's a ghost, and everything's haunted, and that the beautiful mansion he saw was actually a decrepit wreck of a former mansion.  Both this book and that movie have an almost sex scene, too.  No, check that--Quinn and Beckinsale have a scene, maybe the first nude scene with a "ghost" ever on film.  And the dead talk to each other, and there's animosity...Well, anyway, both are credibly creepy, hard to do these days, when we all know the tripes of horror and ghost stories.  That this book succeeds despite that is deserving of applause in of itself.  But perhaps the best thing to say about it is that I read all 371 pages in half a day, and this after finishing another long novel, Straub's A Dark Matter, today as well.  Not feeling well, physically and psychically.  Anyway, a good psychological tale that tips its hat to the works of Henry James, and a few other works of creepiness...though I could have done without the Egyptian gods parts, and the extensive Beowulf references, but you need something to set your writing apart, right?  The ending of the occasional ghost-narrator taking over the recuperating, and coma-resting, body of the main character is sort of inspired, and not believable, and a nice touch, all at the same time.  Another Dan Simmons winner.