This book isn't bad per se but it was fan service Mixed with shadow man and syndacater mystery plot. The latter was interesting at first but in the third section it went downhill: the pacing was rough and the reveals were nonsensica..
I'd still recommend it to fans of the series but know that this book is a notch down to the previous ones (for me) and it felt like a second book for Lyla and the Shadow man (which I thought was the right choice by the way).

If you want to read a great review of this book read ruinpeach's one. It sums up the book perfectly.