I've started to worry about Dave Duncan recently. He's put out a fair number of new books, and a number of them haven't been very good. I worried that either he was cleaning out the closet, or losing his touch. Happily, Portal of a Thousand Worlds is more of a return to form, though not perfect.
I didn't really buy the alternate Chinese setting, but when I accepted it as simply a fantasy universe, it went down better. Duncan has a lot of characters in play. That's fair, in an epic novel that covers a vast landscape, but I found it easy to lose track of which was which, and what they were doing, especially since many of them had similarities, and they changed names at the drop of a hat. Still, aside from that occasional confusion, the plot moved smoothly and quickly. As is usual for Duncan, the tone was relatively light, and the characters (whatever their names) engaging. Women don't come off very well; it's a very male-centric world. That works better in an alternate historical China than in a modern fantasy, but that's not how I was looking at it. Every now and then even Duncan seems to lose track of his setting, introducing tennis metaphors, and a few other oddities.
While Duncan's characters and their machinations kept me interested, the book is steadfastly pointed at the opening of the Portal and the revelation of its mysteries. Here, Duncan lets us down, with a fairly thin ending that leaves very many things unexplained. The book works reasonably well despite that, because of the strength of the characters' interactions, but it would have been much stronger if it had either focused on that to begin with and left off the teasers, or put more energy into the finale.
It's an enjoyable, rapid read despite its size and complexity, and mostly satisfying. Duncan's still got it, when he puts his mind to it.