House of Reeds is apparently the sequel to Wasteland of Flint, and the story of its protagonists will continue in Land of the Dead (which, according to Wikipedia, is out next month). I haven't read Wasteland of Flint, because my library doesn't have it, and neither do my local used book stores. With that disclaimer out of the way, on to the meat of the book.
Harlan is a good goddamn worldbuilder. He's apparently written a whole whack of alternate history/fantasy epics for Tor, as well as working as a game designer, and it shows. In this series, he's merged alternate history with space opera and military SF, creating a weirdass background that sucked me right in. The basic story is this: sometime around the 1500s, the Aztecs conquered the world. They could do this because a few hundred years earlier, a big fleet of Japanese refugees, fleeing the Mongol invasion of Japan, washed up on the shores of North America. So Aztecs got to learn all about things like steel and horses and gunpowder, and then they went and beat the crap out of most of Europe. Take that, Columbus! Flashforward a few hundred years, and the joint Aztec-Nipponese space navy is still kicking ass and taking names. Our heroes are all either members of the Aztec-Nipponese empire, or they're on its fringes trying to survive.
The story takes place almost entirely on the planet Jagan, where the Aztec secret police/priesthood is planning to deliberately incite a small brushfire war, a flowery war. They want to throw one of the younger sons of the Aztec emperor into the mess. He's a drunken idiot, so he'll either man up and cover himself in glory, or die and please the gods that way. His Scottish bodyguards will have to try and make sure it's the former. Meanwhile, Gretchen Anderssen, the xenoarcheologist and hero of the first book, has been ordered to Jagen to study a possible ancient and powerful artifact, and Captain Mitsuhara Hadeishi of the Imperial Navy has just come into orbit after a long patrol, looking to resupply and refit his battered ship.
The elements of a great epic story are there, but Harlan never quite makes them gel. Characters are defined well to start with, but we don't get below the surface of most, probably because there are so many conflicting plot threads – there are at least four viewpoint characters that I can recall just from Hadeishi's ship. Then there are Anderssen and her team, the bodyguards, the wicked old spy pulling everyone else's strings, diplomats, the various alien locals, and so on.
A word on those aliens: Harlan can't do original alien critters. We get a cat-alien, a whole bunch of lizard aliens, and a brief cameo by bug aliens and a super shapeshifer alien. They all fall into categories such as fierce predator, wise old mystic, or barbarian warrior. The fact that they come off like the clichés of how other races were portrayed in Victorian fiction isn't a good thing.
Just when it seems things are settling down in the plot, Harlan suddenly pulls out the big guns, ignites the war, and turns the last third into one long chase scene/gun battle. It's not that I don't like action sequences, but these go on and on and on. They're also disturbingly colonial. Almost every fight involves small numbers of well armed humans holding off hordes of less-well-armed local lizard people. It's like Rorke's Drift, one of the battles of the Sepoy Revolt. Or maybe I'm going too far back, and it's just a Black Hawk Down homage. Harlan lovingly describes how the massively overpowered weapons of the humans chew up hundreds of lizard guys at a time.
The plot about the alien device of great power also never comes together. I'm not actually sure what it did, in fact. I think it did something, and there was some attempt to explain exactly what near the end of the book, but it seemed sort of inconsequential by then. Another key plot, a thread involving a hidden alien and the prince's bodyguards, seemed to be deliberately leading into the next book in the series, and was left dangling.
For fans of well-written military SF or space opera, I'd say give it a try, especially if you can find the first book in the series for background. But it just never quite came together for me.