It was ok. I really had high hopes for the series after coming to J.L. Bryan from the Paranormals Series (Jenny Pox, etc). The writing style is very similar, but where Paranormals still translated into a more mature 15-18+ YA novel series despite the simplistic writing style, The Song of Magic Series (of which Fairy Metal thunder is book 1 of) is definitely a very simplistically written series that translates into being meant more for Young Adults in the 12-14 range.
But don't take that as I didn't like the book. Overall I enjoyed (and finished) it, and the story was interesting and one that I haven't seen explored much with fairy authors... I only really found it disappointing in that, for me personally, there wasn't enough depth or actual character development, and that compared to Paranormals, it's certainly meant for a younger age range in the YA category. I just wouldn't recommend it for anyone looking for a more mature YA novel centered around fairies. BUT, if you enjoy the more whimsical Fairy story with little to no violence, conflict, etc, then this is certainly a cute story you'll enjoy.