What a pity, to see Scalzi fall prey to the second book syndrome. While the first one had the beginnings of an infinite number of interesting premises - people who can skip from robot to robot while imprisoned in their actual human bodies - this one didn't take an interesting turn like the first one did.
The first novel's twist was based directly on the makeup of the people and their environment. This second one was more trite - more of a standard murder mystery. Scalzi clearly struggled with it - heck, he says so in the afterword. And I think it's because he couldn't figure out a better twist in his plotting. It's clear he was trying to fulfill those pesky contractual obligations.
He wrote a surprising number of scenes that involved the same setup. After a while, when the enemy has already arrived before our protagonists get there, you have no option to to begin to expect it. This must have happened at least a half dozen times (really). Repetition is a death knell in these kinds of novels.
Otherwise, we do get introduced to a new sport, one designed specifically for this world. We get a fake game of it (created by Scalzi just for a later scene, once again, far too bloody obvious). But otherwise, we don't get to watch a game. More's the pity, and it shows that Rowling he is not and Quidditch he did not invent.