Well that was break-my-brain amazing. XD 
 Yoon Ha Lee has taken space battles, mathematics, identity issues, loyalty issues, and war and spun them all into a reality simultaneously alien and oh-so-very human. There's an overt strangeness to the society and physics that the author doesn't take the time to explain (put simply, the author assumes you have the patience to figure it out) 
 The (physics? magic?) system is amazing. The characters are all living under a "calendar"... which is essentially a way of warping reality based on the unified belief/practice/rituals of a sufficiently large population. In other words, a ruleset. Now, while 'invariant' technology (stuff that relies on day-to-day physics, I suppose) exists, it's slow. And you can do a lot more with 'exotic' technology... but exotic tech is calendar dependent. This only becomes a problem when you run up against competing calendars/rulesets/reality engines, because your stuff doesn't work the way it's supposed to. Enter the heretics, which the hexarchate has a vested interest in getting rid of for the reasons previously listed. 
 Kel Cheris is one of the coolest characters I've met in a book in a while, and Jedao--I'm not even sure where I want to start with him. He's a cold-hearted bastard with his own LONG-term game plan, but he's also intriguing, and even identifiable. The character dynamics were masterfully played--quite frankly my head is still spinning a little. 
 All this to say, "Yes. Go read this book." (I mean, no it's not for everyone, but it's going on my favorites shelf, so...)