Props to the author-duo for keeping KD fresh and exciting. Yes, I am sad the series is winding down. I think it's important to end on a high note instead of continuing just because and the books becoming less interesting/more frustrating, etc.
While this was much more serious in tone, the banter/affection the characters have is all there. Nice surprise regarding Christopher. Kate showed her humanity in this one and had some fumbles and struggles to overcome. There was a birth, death, Ghastek choosing where his (and the other navigators) loyalty lay, a battle.
This was hinted at during the book: