These books have steadily been getting better and better and better, or perhaps it's just me getting so far invested in the stories that I can't even tell the difference anymore. 
 Either way, this says very great things about the books. :) 
 I am invested as hell. 
 Aaronovitch's UF writing is rather unique in that his mystery writing is unparalleled, the magic system is firmly grounded, explored, and interesting, and the MC in Peter is just a lovable nerd. Never mind that he's an apprentice wizard working for the London police force or a small subsidiary called the Folley, this is really just a fantastic police procedural full of unpredictable mysteries and grabbing reveals. 
 This book, however, takes everything that has been building up in the previous five books and focuses yet again on the Faceless Man and poor Leslie. In my opinion, this was a squee-worthy move on the author's part. At least, I was practically slathering with all the great reveals and directions it took. 
 Dealing with the rich and the issue of the other mystery was well enough and a nice departure, to be sure, but getting back into the grand arc story was simply delicious. 
 And now I'm stuck in the unenviable position of pining away for book seven. Who knows how long it will take? Alas! 
 Do I recommend this UF? HELL YES. It's one of the very best. :)