I think one thing that could help the story is an evil character.
The idea of having a more defined villain is an interesting comment. On one hand I've enjoyed the fact that there isn't an obvious opponent, adversary, singular Source Of All Conflict And Evil so far. The absence of such makes the story more mysterious. On the other hand, I mentioned in an earlier post how I felt the characters were all too passive, and I think this is part of it -- their actions have little urgency (for themselves or us) because they have no defined opposition acting on them, and for them to act on and react to.
It's like what Elantris would have been with Hrathen's POV taken out -- there would have been more mystery but less tension. I think with this book, without that recurring insight into the enemy, the challenge is to keep the mystery but up the tension. You can look at a lot of traditional mystery/thriller sources for examples of this; for me, the important things are that we care about the characters (which means I think we need to get to know them better, learn more about their interests and see them in a wider range of emotional situations) and we need to feel they're in real, imminent danger.
(It occurs to me that there are a lot of similarities between Warbreaker and Elantris, BTW: a young woman leaves her home in a political marriage to unite two countries; the country she goes to has form of government based on mass-exploitation; she has little/no access to her husband until late in the book; an organized religious group seems to be making a play for power; a member of that religion experiences some religious doubt and feels unexpected compassion for the female character. There are plenty of differences, too, of course, but not knowing what you have planned, this may be something to keep in mind.)
I said in my earlier posts that the story had felt "young adult"-ish to me, and one of the reasons I said that was the absence of what joevans3 calls "evil." I would instead term it the underdevelopment of things "dangerous," by which I mean not just things that are literally dangerous to the characters, but rather that full-fleshing out of ideas that says something interesting about humanity, that can sometimes make readers uncomfortable. Basically there seem to be a lot of potentially "dangerous" ideas and story elements that are treated with kid gloves: the moral/psychological implications of the Breath idea; religious certainty/uncertainty; mercenaries, criminals and the underside of a city; the question of ends vs. means; political espionage and sabotage. This may be a feature of the story as a first draft or it may be a conscious decision to stay away from these things to make the book exclude as few readers as possible. I mention it mainly to make sure this is a conscious decision, because I think the author should always tell the story he wants to tell -- and obviously in this case we don't yet know how it will end.
I agree, I have wondered what Siri and Vivenna's father has been doing. At times it's felt like there is too much going on -- so many characters, so many aspects to the magic system, that none of them are getting the attention I think they deserve. I don't know how far along the story is, hopefully this will change by the end (and the fact that I want to know more is a good thing).
One question on this chapter: how much time has Siri spent teaching Susebron to read as of this chapter? He seems to have, um, picked it up very quickly. It's hard for me to conceptualize, but if he had both memorized the alphabet and his storybook, couldn't he have taught himself to read/write at least the words in it? (Or is this, as you may answer, the reason he's learned so quickly?)
Regarding the previous chapter, Lightsong has definitely become my favorite character, after a slow start. He himself confessed he was boring at the beginning, but he's gotten more interesting recently, as he's become more interested in what's going on around him. Also his mystery is interesting. Who was he in his previous life (we have hints: a woman, a boat; he died five years ago; he was "the best of men")? Who was Llarimar? Was Lightsong's death and Return by plan or accident?
It seems Lightsong is being set up to find something meaningful to offer his life for in sacrifice...but what? Speculations: is it possible for a Returned to give life to a Lifeless? Something relating to Siri, as she's the one who has rewoken his interest in life? Something to do with Llarimar, since Lightsong has the most connection with him? Something completely random; in some ways fitting given Lightsong's somewhat random approach to life?
MattD