While I don't typically read from the Young Adult age range, I picked this up on a whim and can say that I did like it for the most part. In terms of age appropriateness, this felt way closer to Middle Grade than YA, despite the MC being 15 years old - the characters read much much younger, in both dialogue and through their actions. I enjoyed the first 35-45% of the story - the world-building and characterization at the beginning was interesting and had a good pace, but once I got to the 50% mark, the pacing changed drastically and everything became very 'telling, not showing' - also Fletcher's decision-making and thought processes felt more juvenile than any average 15 year old boy. 

Overall, I think this is a good story for a (very) young audience, but more so for fantasy-beginners as many of the actions and characterization could seem cheap/underwhelming for any reader that has read more than a handful of fantasy novels.