I love this series, and it makes you think about what life would be like if this actually happened! The characters are all believable and each have their own problems to contend with, though in this book there was a lot of changing point of view so I sometimes lost track if I hadn't read about a certain character in a while xD I found it surprising that, even though Sam is the main character, this book didn't follow him as much as the other did. Instead I feel like this book balances out between all the characters, not just Sam, but I guess this was to emphasise that he wasn't really himself, and things start to fall apart :/ You really feel sorry for the characters and in touch with them, for me I felt bad for both Mary and Diana especially, since they have a rough time of it in this book. At the same time you really hate some of the characters, like Zil and Caine (though I enjoy reading about them the most xD). The main thing is, I never felt like skipping a chapter or a boring block of text...it was all good, gripping stuff :)
There are plenty of cliffhangers and the content is super, so I highly recommend you read this if you haven't already ;)