An exciting interlude

Unlike my entourage, I was not particularly disappointed not to follow John Perry in this volume 2. We meet regularly, secondary characters, the two people who will be his relatives in the next book, and I found this interesting presentation.
The style of John Scalzi is still fluid and pleasant, punctuated with humorous touches, and that mastery of the art of narrative is reason enough for me to gratify this book 4 stars.
The extra star is for the best interest of the book: Both subjects are that of the birth of a traitor (figuratively but also literally!) And of the identity of a being (for Ghost Brigades soldiers but also for Obins). I enjoyed being sensitive to the arguments of the traitor in question, particularly with regard to the Earth, which seems to me from the beginning (the "Old Man and War") curiously similar to the one we know. The difficulty of developing a personality for ghosts Brigades soldiers because of their birth without children without parents, but also because of their flash formation - before being thrown into the action and the permanent risk of death imminent - is developed with great finesse, leaving ample opportunity for reflection.
Another fundamental question is raised several times (especially when meeting with curious turtles) on the definition of humanity of a being: how can you change a human body and let her qualification precisely "human"?
Finally, the outcome is satisfactory and introduced well the next book, "The Last Colony".