I didn't realize that I hadn't posted since the last Scalzi book I read. Of course I've read other stuff in between (it's been a good month: 3 Repairman Jack books, Varley's "Red Lightning" (meh)... I'm on a tear.
Anyway, "Ghost Brigades"...
Excellent follow-on to "Old Man's War" but you don't need to read one for the other. Some carryover characters, but no John Perry.
My only gripe is that he is a little too clear that he's standing on the shoulders of giants. OMW was described as a modern take on "Starship Troopers" and "Forever War" and that certainly fit.
In GB, he name-checks several SF writers, both in character names (a group of Ghost Brigade troops took names after writers), and in one character's research into artificial beings, from Frankenstein's monster on up through Asimov's robots and Heinlein's Friday. He specifically mentions "uplift" a concept coined by David Brin. It gets a little tiring to see things that obvious, but it's only his third novel... he'll get better and better.
GB talks a lot about the ethics of artificial beings and imposing memories on another head, but missed some of what I consider exemplars on the subject: Brin's "Kil'n People" -- those people are temporaries, and there's no compunction in killing off duplicates, as you can re-incorporate their knowledge. C.J. Cherry's Azi in the Alliance/Union stories, especially "Cyteen" are probably the closest equivalent: The Azi are generally interchangable slaves, tape-trained. Cyteen's main character has some of the same characteristics as Scalzi's Jared Dirac: designed to be -- or become -- someone else, where does one person's individuality and rights come from?
There are some nice unexplored concepts that could be part of another book, or just round-table discussion: Where do the Special Forces personalities come from? They are 'born' fully formed, with software serving as a crutch for developing conciousness and self. Some are lazy, some sarcastic, some enthusiastic about blowing stuff up... Is it genetic, or subtle interactions -- we're back to nature vs nurture. Some of the smae came up in another recent book whose name I've forgotten, where one of the major characters is of the "Russ" geneline, thousands of introverted expert security officers, with common genetics, but each raised from childhood individually (but at a Russ school).
One other cross-book concept: The "integration" of Special Forces soldiers, through their "BrainPal" computer links, brings back Haldeman: "Forever Peace" posited that if you get in anothers' head, you'll empathize enough that war is impossible. That's not the case in GB -- although integration is key to the function and efficiency of the Special Forces -- but it's interesting that the first in this series touched Haldeman's "War" and this touched "Peace".
Read "Ghost Brigades" then go read some more stuff.
Books by John Scalzi: The Ghost Brigades