Let's be clear, here. The strength of The Half-Made World is the premise, and not the characterization. It's sort of reminiscent of China Mieville's Bas-Lag series in that respect, though not quite as imaginative.
The Half-Made World brings us a re-imagined American West, where two great forces--the Gun and the Line--squabble over territory and power in the "made" frontier. Beyond the made world are literal wildlands, ruled by the indigenous, troll-like Hill Folk, where the natural world isn't just "untamed" in the usual sense, but a place of strange and phantasmagorical flora and fauna.
The tamed parts of the West consist of the typical frontier towns and larger, industrial cities, run by the Line.
The Line and the Gun are essentially the manifestations of order and chaos on a hyperbolic scale. Both are run by preternatural overlords, demons essentially, who manifest as either guns (the Gun, duh) or train engines (the Line).
The Line is order run amuck, if that's possible. It's an authoritarian's wet dream and for that matter, an anti-environmentalist's. Followers of the Line live in gritty, filthy, over-industrialized cities, fearing pretty much anything natural. They are a pale anemic lot, probably because they won't eat their veggies or go out in the sun. The upside to all this nature-hating is that they've got all manner of bad-ass technology and in the war to win the West, the Line is beating the pants off the Gun.
The Gun is a much more loosely run outfit, where agents are bonded to and carry a demon-possessed gun. Never runs out of ammo, self-loading, serious firepower. With no strong organization or infrastructure, the Gun's M.O. is basically guerrilla warfare.
The players in this drama: Liv Alverhuysen, a psychologist and former college professor, who heads west from her comfortable life in the east to work in a hospital that cares the war's wounded. Lowry, an uptight and priggish commander in the Line, who, thanks to a series of unfortunate incidents, keeps getting promoted. And John Creedmore, a middle-aged agent of the Gun who is called out of retirement to find and retrieve the novel's McGuffin.
The McGuffin is General Enver, most recently a patient in the hospital where Liv works. Once the commander of the upstart Red Valley Republic's army, the General is now a drooling shadow of himself, thanks to one of the Line's mind bombs. The General purportedly has information regarding a weapon that could spell the end of the Gun, Line, or both. Lowry, with an army at his back, and Creedmore, with his snarky personality and bad attitude, are tasked by their masters to get Enver. Liv finds herself caught in the middle.
Honestly? It's with the characters (and to some extent, plot), that the novel loses momentum. The story sets up a "mad chase across the hinterlands" premise, but the actual race is more of a meander, all tortoise, no hare. Outside of Creedmore's skirmish with the Line in a small town, and later, a battle with a snake/dragon beast, there isn't much action. Also absent is any sense of danger. This probably because Lowry, Creedmore and Liv are all loners, with no emotional attachments. Which makes it hard to use to ye old "kill off a friend" ploy to induce a sense of menace plot. And...none of the three are ever in much danger, period.
Therefore, The Half-Made World's primary appeal is the setting. It's the kind of place, given more interesting characters, or the potential for an interesting "ship," that might be worthy of fan fiction. (Not that I'd be the one to write it.) As it is, the premise alone is compelling enough to make me want to read the sequel. Hence, the four-star rating despite the hum-drum characterization.