Quite excellent. It turns out it's a sequel, and I haven't read the original yet, but it stood up just fine on its own. And now I really want to read the first book.
I had noted that Hambly is a pretty feminist author quite some time ago -- the Sun Wolf books made me first think it -- but I really noticed it in this one. Not only are the vast majority of major characters female (and that includes bad guys as well as protagonists and side characters), the thing that I thought was particularly neat is that it wasn't just about women using magic to save the day, it was also about their relationships with other characters. Plus the setting has gender issues for the characters to play against. So it felt like it was more than just flipping a coin to pick pronouns in an otherwise genderless story (I'm looking at you, Honor Harrington), it was an actively feminist fantasy adventure story. Which is cool.
I also am starting to read with more of an eye toward how stories are constructed, and I was really struck by the way the author kept ratcheting up the tension and the stakes. Like, every time you think they might be getting somewhere, let's make the situation just a little bit worse.
It's a very well-written book. I would definitely recommend it.