The flashback is the weakest of all foreshadowing, and it is the device that ruined this book for me. It's a shame too, because Thomas H. Cook uses other foreshadowing as well--hints about the deadliest sin being pride, allusions to the consequences similar characters faced in great literary works. The flashbacks were confusing at best and disruptive to the pace of the story at worst. I don't mind so much if the entire story is a flashback set within a frame story, or if there are flashbacks to a single period of time. But in this case, Cook employs flashbacks to several different periods in the protagonist's life, and this detracted from my enjoyment of the book.
Most of the characters were flat, without much to recommend them. There are a few exceptions, of course--the main character is three-dimensional, if increasingly paranoid. Eddie Miller has depths to him, the exploration of which becomes one of the central pillars of the plot. In a way, the flatness of the material antagonists, such as Dirk Littlefield, serve as a counterpoint to the turmoil within the main character, emphasizing that the true tragedy is a psychological one, preying on the mind and not the body.
My overall impression of this book is that Cook deftly plays on his themes. The struggle is interesting, if not very intense, although toward the end I felt a distinct lack of sympathy toward the protagonist. However, the book itself felt slow, and the prose style was mediocre. While it was not a waste of time, I'm not sorry that I'm finished it either.