AHA, I have a THEORY. (Did you really think I wouldn't?)

This theory is based on having read rachelmanija's review, and on someone asking me, "Why isn't there a bigger Cashore fandom?" Because even though I did, very much, like the book, I finished it with zero impetus to write or read fic about it, whereas with most books I really like, there's at least some measure of "huh, I'd really like to see this story extended, and whatever happened to this character?"

Anyway-- I think it's what rachelmanija said: as an allegory, it's really good, and as fantasy worldbuilding, it's incoherent on the large scale (I didn't notice the mental health incoherencies she points out, but although I liked the ciphering I was disturbed by how it wasn't thought-through how it slotted into their language system and how the language interacted with their history, etc.). So if you like allegories (which I do), it makes it more likely you'll like the book (which I did), but otherwise, probably not so much. Nothing to do with soul ;)

(And it made me realize that it's partially coherency of worldbuilding that sells me on a fandom. If there's nothing to hold on to when you write a fic, what's the point?)