Having read this right after "The White Dragon", I'm not entirely sure how well I can comment on it as a standalone books, rather than as an exploration of what was going on "meanwhile, back at the farm".
The second half was better than the first - I seem to prefer the Southen Continent stuff. Also, when I first read this series (somewhere between 10 and 12), I completely failed to register most of the sci-fi elements. Funny, they're not exactly easy to miss. Still, I like her marriage of soft sci-fi and fantasy: she does it well and if not all the characterization is as distinctive and as well wrought as I could wish, the world of Pernicious more than makes up for those deficiencies.
Also, I rather think I favor those books I discovered during my...formative years, let us call them.