This book was fine. I just finished reading the entire series, and I'd say that the first book is the best. Listen, I read the whole series. I enjoyed it. That said, it doesn't come close to representing a pinnacle of fantasy writing, and is best describe as an easy summer read/beach/airport book. It's the Mammia Mia 2 of books. It's got a lot of weaknesses, but on the whole, eh - it's just entertaining and was quick.
Strengths:
Characters are likable
The world itself is an interesting place that I wanted to learn more about (I haven't yet read any of Hale's other works in this world)
The magic system was somewhat unique and interesting.
Narrated by my favorite audio book narrator, Kate Reading (which is entirely why I picked it up in the first place).
Weaknesses:
The plot and entire book was entirely too predictable.
Filled with fantasy tropes.
While there was, at least, gender parity between the characters, we didn't really see any variation in "types" - almost all of the characters are youngish, warrior types, whether they're men or women. They essentially just have different weapons/abilities. It would have been nice to see people play different roles in the series.
The main characters are ridiculously overpowered, with little-to-know explanation as to how they got that way. The main characters also succeed far too easily - things that would, in reality, take years to master, take the main characters days or weeks - just because they "persevere" or "have suffered."
Hale's conception of this world is far too black-and-white. The bad guys, a huge group of people, are nearly monolithic in their bad-ness. If this is YA, it'd be good to model or do more than extremely simplistic hand-waving, that the bad guys have complex and varied motivations.