First, the entire series is incredibly refreshing. Epic Fantasy is generally "conservative" in metaphor at many levels. The hero (and there usually is just one) is typically male, white, heterosexual, etc, etc, etc; the bad guys are typically of color, not Euro-ish, effeminate even sometimes. In Acacia, the heroes are varied in race, home, sex, motives. It takes many of them a long time, and a lot of mistakes to get to the point of doing "right."
Next, the conclusion of the series isn't a nice, tidy fix by a savior. It's just a hope of something better. I LOVE that.
Finally, Durham knows how to finish a series. Who finishes a trilogy in four years? Who finishes a trilogy in three books? LOVE THAT. Of course, I love the torture that is SOIAF and WOT too . . .
I'm going to read Pride of Carthage just because I know this dude can write. And he's on my must pre-order list from now on. Ten out of ten and the best book I read this year.