Firstly, this is not a novel, at least not a standalone one. Firstly, you should have read Scalzi's Old Man's War trilogy before reading, and secondly, it does not have an ending, it just stops. I can only assume there will be more stories in the OMW universe; however it is an open question as to whether I shall bother reading them.
About a decade ago, John Scalzi published OMW, got a blurb saying it was like Heinlein (Starship Troopers variant, not I Will Fear No Evil or Time Enough for Love variant) - and it was pretty darn good military sci-fi. Then the next few books set in the OMW universe got squishier and squishier, to the extent that vol 4 was not only a retelling of vol3 from a different viewpoint, but that viewpoint was of a teenage girl and the book was targeted at a YA market.
Scalzi's a pretty good writer, so he could pull it off. But at some point it stopped being what made me want to read it in the first place. Apparently, Scalzi no longer to wanted to write it either, so he took a 5-year break from it.
The Human Division is, then, the triumphant return…but while its good, and not as limited as you might think from being assembled from 13 standalone e-pub stories, its just that it does not have any closure. It ends. Threads are not just dangling, the whole loom is just sitting there. Its also more intergalactic politics than military sci-fi (but I was at least aware that ship had sailed some time back).
Honestly, I'd say wait and see if there are sequels planned and actually published before you run out and buy this. Otherwise, this smells like a scam to take advantage of e-publishing and micropayments, and while fixing up short stories into a book has a long and honourable history, well, I've never met a collection with a softer ending than this before. There are some good moments here, but no (or very little) payoff for a lot of buildup.