This book was interesting, but it felt like you were inside a Michael Bay movie, to much action explosions and dead of inconsequential characters, and yes consequential characters also die, this is a collections of 4 books and the last one is the best one, the most coherent in itself, but darker, and sadder in a collection of books already dark and sad.
The problem with the books is that the history at least in the first three makes no sense you ask the same thing through all the history, Why? and Why? and WTF? and when the explanations finally comes (this writer likes cinematic twist Shyamalan style) your reaction is Bullshit and that makes no sense, you suffer three books of torture porn (saw like) and you get that kind of explanation ending!!! even the Stephen king giant spider endings were better. Any way all the movies analogies are on purpose when you read is evident that this books were written to catch on the dystopian craze and get a movie deal, all the action and explosions, you can practically see the shaky cam, the personages are there just to be kill not having any substance, its pretty easy when you just establish they have no memories, most have no name so their deaths are meaningless we have 4 protagonist and 40 red shirts used to give extra seriousness and darkness and maybe an pg 13 rating.
the forth book the prequel was much better but is really similar to a post apocalyptic zombie movie, dawn of the dead type and has a similar dark ending, but is an emotional ride, with well develop characters and a history that has internal logic and coherence, i will recommend to read all the books to read the prequel or best yet, just read the last one, the prequel, The Kill Order.