I agree with most of what is said. I will miss seeing Saiman be his weird self, and seeing more character growth in these last two books than we've seen in the rest of the book for him.
My reread is taking longer, ir part because school has started, but in part because I don't want to be reminded about all that character death in the final battle. I was in part really amused by the epilogue, and in part really upset. I do think that Julie should have handled it better, but I also recognize that she is still a teenager, with her still developing brain, and an irregular childhood. I'm also upset that she apparently left without telling Derek anything. Yes, they're not dating, but they very obviously are close, and you don't just abandon your friends like that. Erra being resurrected and (to put it mildly) upset about it really made me laugh.
For future short stories or books, I would love to find out how Julie found out about Hugh (though I suspect that will be covered in the Hugh books) and I would love to see some of the adventures she has with Erra. I know both of the Andrews have mentioned being a little leary about how much Julie would change between the series they have in mind and the kate series, and how the readers would react to that. Some e-book short stories might fill the gap enough to not surprise/upset the readers as much.