I tried to read this book, I really did. The premise was fascinating. However, all of the dialogue was phonetically written in the dialect of the period, and I could NOT get through it. It was driving me crazy. I got about ten pages in and had to stop.
When a book takes place in France, you assume the characters are speaking French, and the author is translating for you. For a book taking place in midevil Scotland, I would assume without being told that everyone spoke in a Brogue. They probably all spoke Gaelic. I do not need to try and translate that.
So, it's probably a great story, but I was unable to read it.