It's unusually episodic for a Carey novel - there are three distinct parts, the "British" bit, the "French" bit and the "Chinese" bit, with the journey from "France" to "China" somewhat handwaved away, and I almost felt once we reached the Ch'in empire that we'd spent 400 pages preparing for the main bit of plot. But perhaps we are working into Carey's world in a new century; we need to start off in old familiar territory, to get a sense of how it has changed, before exploring the newer side.
Moirin, of course, shags almost every attractive high-born man and woman in sight (and one coachman), and pays perhaps a bit more of an emotional price for it than some of Carey's previous protagonists even if the sex is a bit less kinky than in previous volumes. Much more than in previous volumes, Moirin and her friends and relatives must engage with non-human, non-physical entities - the great bear spirit in "Britain", the dark powers summoned by her student friends in "France", and the dragon in "China". I found it interesting that an element of the internal Ch'in struggle was the use of gunpowder for military purposes, with the very firm conclusion that it was inappropriate for this world, which must stay firmly medieval and magical in its technology.
Anyway, very engaging as usual, and a reasonable starting point for those who have not read the previous two trilogies, as it is much less closely linked to them than they are to each other. I have the next volume on the shelf, and must make sure to get the last as well.