I finished this a few days ago and I have to say that I can see why John Scalzi won the John W. Campbell Award for Best New Writer for it. For a debut novel, the reading of the novel was effortless. The prose was so smooth you barely even knew you were reading at all, throughout the entire book. Incredibly smooth reading.
As for the story itself . . . well, you need to know a few things about me before I get into it too much. First of all, I don't read much SF. I'm almost purely a fantasy fan. So keep that in mind. Also, I have never read Heinlein and one of the main points brought up by anyone who has read Heinlein and then Scalzi is that Scalzi is apparently channeling Heinlein from the afterlife. I can't comment on this, because I've never read Heinlein . . .
But I have read Scalzi and I liked it. As I said, the read was effortless on my part. This is basically the story of a man who enlists at the ripe old age of 75 (the youngest age you can be to enlist), gets trained to fight, and then goes off planet to fight. The first two-thirds of the book are about his enlistment and the surprises he gets once he's off planet and is out discovering what enlistment really means and that the world off planet is MUCH more interesting than what he's known all of his life. And that's pretty much the plot. A sort of more serious plot emerges in the last third of the novel, but it isn't really as significant as what has followed before. This is the man's journey, and that's all it's intended to be.
That being the point of the book, I kind of had a minor issue with the fact that we don't really get emotionally "into" the character in the book. This would be my biggest complaint about the book: the lack of any intense emotional connection between us and the character. It's written in the first person, which means we should get intensely personal with the character . . . and we don't really. Or at least I didn't. One of the most emotional aspects we get from him is the death of his wife before he enlisted. I wanted this death to be felt more, especially since it has significance for the last part of the book. And this IS the most significant emotional response we get from the main character . . . but having that be true for the book as a whole . . . I wanted a little more. I wanted this level of emotion for the friends he meets and subsequently die (it is a war, people die, I don't think I'm giving away anything here), and something bigger, something deeper, for his wife.
But that was my only issue as I read this. There WAS emotional connection, don't get me wrong; I just wanted it to be developed more. And I certainly intend to read more Scalzi, because the writing and the story were GOOD. It was easy to read, with nice touches of humor in appropriate places, and it was a human story set against an alien universe. I've already bought "The Ghost Brigades" in fact. I'd certainly recommend the book.