This series just keeps getting better and better. The artwork and writing is consistent throughout the series so far, so nothing there going wrong to drag things down. As such the rating rides entirely on the writing and story development, and that just keeps improving volume to volume. I can’t speak for other readers, but I have really become emotionally invested in these characters, and as such really want to know more about them and where they are going as characters. This is not something that very many writers have been able to trigger for me, so to me that speaks volumes about the writing involved here.
As to features of the graphic novel format, I love the key to the keys in the back of the volume. Incredible added value to the volume, especially when it is such a premium binding job. I have seen lesser products, bound cheaply with no real added value charge as much or more for their volumes, so finding this much value in this volume (and the others in the series for that matter) is incredible. After all, how many times do you find a hardcover binding with a fabric bookmark as part of the binding at the $24.99 price point? Or for twice that price for that matter? Incredible value there!