To me, spin-off series are not really necessary, it has to be done really well to make me forget about the originals (so basically, in this case, Magnus). 
 Since I first read Falling Kingdoms, I've been obsessed with this world, and the characters, and basically everything Falling Kingdoms. And of course, being a fan of the series, I needed more (even though I didn't know what to do without Magnus at first). And damn, this book was good, really really good. I like the plot a lot, I mean a secret society, with bad guys, murders and magic, I'm sold. I just think that Morgan Rhodes can make me love any story or character now. Even though, I wasn't quite interested in the Maddox parts, I LOVED the Crys and Farrell parts (and I know, my brain knows he is an ass, but also it's not really his fault, is it?), like I said secret societies are just so good and interesting, and damn, Hawkspear Society is a good one. 
 I just absolutely love these stories. Falling Kingdoms is still my favorite, obviously they are, but that was still really great. And I'm gonna stop now, because this review doesn't make any sense.