If you are looking for a zombie book this is not something you should pick up. Xombies, with an X for the virus "Agent X" that has attacked the world, are only present for about the first fourth of the book. The author created some pretty good cliffhanging chapter endings so I did want to keep reading but I'm not sure if it's because I was totally gripped by the book or just because I had no idea where the book was going to go next. The book does take a very sci fi turn for the last 3rd which I'm very hung up on if I like it or not. It wouldn't have been a problem for me if the first two-thirds were so different. This book is sort of a mixed bad for me. It was better than I expected but I'm really not sure where the author is/was going with the story either. Still haven't decided if I will pick up the second book when it comes out just because it was such a story change at the end.