SUMMARY REVIEW WITHOUT SPOILERS: Overall, I really enjoyed this book. The story is original, and I don't get to say that as often as I would like. Cronin has a way of writing that gives the reader such a clear image of the scenery he describes, and of the atmosphere surrounding his characters. There are some sections of the book where the writing could have been better, but over more than 870 pages, I think I can forgive the author for a handful of clunky paragraphs and misused words. The biggest problem I had with the book was the structure. There were two main time periods covered, and the first took up less than a third of the book. This section of the book was so visceral and disturbing, and so well written, I really would have liked for it to go a bit longer and balance out the book at the same time. The story jumps ahead 100 years, and the tone goes from modern horror to more traditional fantasy. I didn't mind this at all, as Cronin did a masterful job of interlinking the stories from the two time periods. I wasn't particularly satisfied with the ending, however. I got the distinct sense that at this point the author knew there was going to be a sequel and was setting it up. There was some resolution to the story, so the reader isn't left completely hanging, just mildly manipulated. I do wish authors would stop doing this. Overall, it is an excellent read and I'd recommend it to anyone. I'll also be using the term "Flyers, Lish!" for the next several weeks I expect! FULL REVIEW WITH SPOILERS: Overall, I really enjoyed the book. The writing was (for the most part) excellent, and I really felt that I could see the scenes unfolding in front of my eyes. This is no mean feat when you consider what Cronin is describing - nothing that we've ever actually seen before. Even the more mundane scenes were so clear in my mind as I read this. The characters were well developed, none of them based on any one particular template, which I appreciated.What did bother me a bit was the structure of the book. I am a visual person, and tend to have a visual representation of the structure of the books I read in my mind. For me, the first part of the book was under a third of the book. I see this as shades of deep blue and black. The second part (after the hundred year jump into the future) took up almost two thirds of the book, and in my mind stands out in shades of yellow and orange. There is a very small piece in between though, where Amy and Wolgast survive "The Year of Zero", which I see as the white and grey of snow. I found the imbalance of this structure to be a bit irritating, and found myself wishing for a strict editor for Cronin's next book. I really enjoyed the visceral horror of the first part of the book. I can barely imagine anything more disturbing than people deliberately, coldly, inflicting this virus on living people. The story told from the perspective of the test subjects, what they are thinking and feeling throughout this, the way their minds struggled to comprehend what was happening, the unfairness of it all - it was breathtaking. I would have liked to have read more of that.I also thought "The Year of Zero" was a bit misleading as a title for that little in-between section, and I wondered all through the book what even happened to Zero. All the way through, the characters speak of being "one of twelve", but what happened to Zero? Did I miss something?I spent some time pondering what "The Passage" actually referred to also. In my mind, there are several passages going on here - the passage from human to viral, from human to "The New Thing", from viral to death. There are also passages that the world undertakes alongside this. At the beginning of the book, I think Lear alluded to "what dark passages" our lives lead us to, but many of the "passages" turn out to be a relief of sorts.I also spent some time thinking about Lacey's Noah's Ark analogy. She thought that Peter was Noah, and Amy was the ark, herself the waters. I wouldn't have said that Peter was Noah in this analogy - he didn't build Amy, he wasn't even there in the time before the "flood". I think there are arguments to be made for Jonas Lear being Noah.The one time I found myself really angry was when Amy burned the virus vials. It seemed like a hell of a lot of trouble to go to, just to kill this storyline in a couple of paragraphs. By this point, I had started to see Cronin tying up the loose threads, and had come to expect a certain level of symmetry in the narrative. I had been trying to think which twelve would fit nicely with the vials, and then the idea was killed off quite suddenly. There were certain scenes that were so perfectly written, I page flagged them to go back to. One of these was the scene where Muncie dies (767/768). It was just a perfectly written scene. There were a handful of run-on sentences, misused words and poorly written paragraphs, but in a 879 page book, I can forgive Cronin that. One thing I didn't understand was why Peter gave his blade to Greer when he left the compound. I know Greer returned the blade to Peter later on, but it just didn't seem that Greer had given him any reason to do this at the time.I liked the theme of "letting it go" than ran through the book - both the letting go of life, and of the virus. It applied to both the humans and virals in the end. Another related theme was that a lot of the characters chose the place they wanted to die, and the last view they would take in. This was taken to the extreme when Lear picked a spot, dug his own grave, then went to bed.By the end of the book, I was sick of Michael dropping every weapon he ever had. Did that guy ever have a gun that didn't get knocked out of his hand?! I'll also now be using the term, "Flyers, Lish!" at every opportunity.The ending..... what can I say? There's nothing worse than an author manipulating his audience with a cliffhanger. I really didn't expect this for the first book in what was obviously going to be a series. There is some resolution to the story though, and after reading the excerpts in the thread above, I do feel better about it. I think it'll be exciting to see how Cronin ties it all together in the end. I think I would give this book 4.5 stars if half stars were allowed.