This was absolutely my favorite of the Lord John books! And I am pretty sure that's because there was a lot of Jamie in it, and also because it really explains the real friendship between John and Jamie that we've seen in the later Outlander books. I really needed a fix from this world, it is one of my favorite historical / romance novels, and it was wonderful to enter it again, while I am (un)patiently waiting for Written in My Own Heart's Blood :D
This story exlained a lot about John and Jamie's relationship, and also how life was for Jamie while he was in Helwater. It also showed how much Jamie still missed Clare, even after so many years, and it was beautiful how he would always say a prayer for Clare and the baby's safety.
It also helped me actually like John a little more (not that I didn't like him before, but, still!) and to understand him better as well.
It was all written in the well-known Outlander style, and the descriptions of both people and places were well done.