For some reason I was put in mind of the Warriors series when I read this book. Admittedly, I have not had experience with this series before The King's Riddle was given to me, but I did catch on to the somewhat cat-like theme. The main characters within the story were well laid out and there were parts of "medieval" life that typically get left out of many books of this nature which were included here. A king is a king, but he has a friend or two, someone he trusts. Just because a person serves under you does not deny that friendship. I think that touched me the most, the relationships between parents and children (which weren't touched on much in this book, but were felt all the same) and between friends and companions.
I'd recommend this book for younger readers who love adventure chapter books. It reads quickly but pulls you in to the events as they happen through the book. Additionally, I felt that the author had spent a good deal of time working out the culture of the people involved in this book. That shows well in the writing and storytelling and the mystery of a new culture always adds to an adventure of this type.
Note: Though this book was a free gift from the author, the content of my review was in no way influenced by the gifting. The book speaks for itself and my review would have been worded just this way even if I'd gone out and bought it. I also give bonus points for Text To Speech enabling on Kindle format.... but that also wasn't a factor in the above review.