By J. Gregory Keyes. Finally a book that comes to a decent conclusion even though there's a sequel!
This book reminds me so much of Sean Russell's The One Kingdom trilogy, probably just because there is a river that is central to both books. There really aren't that many similarities between the rivers (perhaps they will be revealed in the sequel, which I have yet to read): Sean Russell's is human and kind (although not technically the river), while Keyes's river is definitely strange, inhuman and cruel.
Like the description on Amazon says, this is the story you've read before: spunky princess and immature hero on a quest, but I think it was quite well told this time. The hero finds the mystical sword halfway through, but there aren't any rings of power (that would be going too far.)
This story is about Hezhi and Perkur. Hezhi is an imperial princess, who for all of that seems to be rather extremely ignored by her parents. She starts out at age ten looking for her cousin D'en (I think the apostrophe is a ridiculous conceit), several years older than her, who was taken away by the priests to below the city. In the process she ends up teaching herself to read (and finally being taught by the tricky old librarian) and discovering what no one is able to tell her: the fate of the children who are taken.
What's really shocking is how she never seems to see her parents. She seems to have had no education aside from what she manages to teach herself. When her mother visits her once near the end of the book, the mother says the fact that Hezhi even recognized or remembered her is more than she had hoped for. It leaves you wondering how these people have managed to rule an empire for so long.
Perkur, a few years older at 17, is the other side of the coin. He brashly makes an unwanted promise to slay the river that is the city's lifeblood (for reasons of his own) and ends up summoned to Hezhi's side instead.
The most irritating thing about this book is how stupid Hezhi and Perkur both are. Hezhi starts out disrespectful and immature, thinking that being a princess will let her get away with anything, but I guess she learns that it won't. Perkur is even worse.
The story does start off with an interesting prelude which hints at the greater plan that might come to fruition in the sequel, which I have yet to read.
UPDATE: I forgot to mention the few but beautiful illustrations, one for the beginning of each part and occasionally one at the end of a chapter. They add a nice touch. More books should have them.