I'm a big admirer of Ken Liu. His short fiction is extraordinary, and he's done wonders to bring Chinese speculative fiction to an English-speaking audience. When I saw that he'd written a novel, I snapped it up.
Unfortunately, Liu's considerable skills with short fiction haven't translated very well to the longer format. The Grace of Kings is long, slow, meandering, and often arbitrary. Liu draws on a large cast of characters, and, combined with his low-key style, the result is that we don't feel particularly close to any of them. Kuni Garu, a clever, trickster-type, is fun and interesting, but not particularly sympathetic, and becomes inconsistent toward the end. Mata Zyndu, Kuni's athletic, military near-opposite, accomplishes the unusual feat of starting as a well-formed character, and becoming more and more shallow toward the end. The book reads more as a pseudo-historical text than as epic fantasy.
Liu's world is depressingly gender traditional, with dominant men, repressed women, etc. He uses this to build some changes toward the end, but it feels consciously tacked on, rather than an organic story of progress and development. This is also a world of quarreling, interfering gods, and they play the usual role, though Liu occasionally relies on them for ex machina solutions. Hero isolated against overwhelming odds? No problem; a god may come along and swallow them all up. Some of the non-deist solutions (e.g. how to put out a gate fire) are equally non-credible and disappointing. Others, including character motivations, are simplistic.
The prose is generally good, though not as smooth as I would expect from Liu. However, the beginning is very dense, with lots of data in what are effectively infodumps. The overall structure of the story also doesn't hold together as well as it should. While politics and governance are key elements of the concept, much of the result is low on realism, with political systems more broad strokes than credible constructs. Spies who wear uniforms are not spies, but enforcers. Some of the terminology is odd and feels out of place - "commander-in-chief", for example, is accurate, but has a modern tone to it; "mano a mano" doesn't fit a pseudo-Oriental fantasy at all, and gains nothing on "hand to hand". One gets the feeling that Liu just doesn't have that much experience with the epic fantasy sub-genre, and doesn't know how to handle some of the issues that come up.
What does work is a happy departure from the standard medieval European base to a less usual Oriental base. Liu pulls it off nicely, with just enough neologisms mixed with more familiar features. (Though at one, point, I began to wish for something not decorated with shark's teeth.) It's an interesting, intriguing world with a steam-punky feel to it. I just wish there were a better story to go with it. I lost interest in this one about 200 pages (40%) in.
All that said, it's not a bad book. With its unusual world, broad scope, and good prose, it's better than some. However, it is a very disappointing book from a very talented writer. Happily, it wraps up thoroughly enough that it's possible to drop the series here.