It is a very enjoyable read. It has many of the same characters from the previous 1 or 2 novels. A different narrative voice for each of the 4 parts. Scalzi seemed to be somewhat less snarky, which I think is not bad for him.
Note that 2 of the 4 narrators are female voices. Scalzi, who was prez of SFWA (Science Fiction Writers of America) for a few years recently, has been one of the main warriors fighting against the dumbasses who finally coalesced into Sad Puppies (and GamerGate) - poor oppressed white males, who just want everything to be the way it used to be: manly men without all this obviously wrong politically correct support for feminism, multiculturalism, LGBT rights, etc. [sarcasm] These guys stuffed the ballots in the Hugo award nominating process to create slates where all the candidates were mostly inferior but mostly WASP males (I don't know, maybe they snuck a Slav in there somewhere). But, yay, a couple of days ago they mostly got their butts kicked with "No Award" taking all the categories where they had allowed for no real worthy alternatives. They are, of course, vowing vengeance! You all just wait until next year!
Plus ca change, plus ca la meme!
In the light of that, in addition to the 2/4 female narrative voices, I am going to guess that at least 1/2 of the characters in this novel, lots of whom are Colonial Marines, are female. That wasn't hard, was it? It does not affect the story at all to do this. It does not create any cognitive dissonance.
If all the scripts coming into Hollywood did this, it might fix a lot of the problems with underrepresentation of females in their productions. I personally feel, the more women in any production the better. The FIFA Women's World Cup, particularly the 5-2 final win over Japan, was some of the best soccer I've ever seen - and I coached soccer 9 years and refereed for 12, so I know the game.