The unresolved stuff from Book 5 continues to be unresolved, but this is not a problem, as it seems reasonable to assume that matters will come to a head in Book 7 or beyond. Once again, Duane changes lots of the rules to fit her present purposes... or, to put it in the terms of the book, she alters the kernel of Kit and Nita's universe whenever convenient.
But I'm just nitpicking. It's a good book and I liked it.
I have a few minor quibbles (Duane tends to redefine the rules in every book, which comes across as owing more to expedience than reflecting a more sophisticated outlook), and one major one that might not be a problem at all, if it's addressed in Book 6. (A major plotline from the first half of the book is abruptly dropped, with no payoff of any sort.) But all of that aside, this was a good installment of a good series, and I'm looking forward to reading the next one.