I finally read it and I see now why everyone is talking about this author. This book is seriously so good. One of the classic fantasy novels, to be read for generation to come. 
 A Darker Shade of Magic is fantasy story, of multiple Londons, grey, red, white and black. Some have more magic, some have only little bit. Magic in this universe is alive, black London, which had the most magic, was consumed by it, and the other had to permanently close the doors between them, in order to prevent magic from black one sipping through. 
 There are few people, very rare, that can open the door between them. Kell is one of them. We follow his as he travel between royalties of different Londons, carring messages and smuggling trinkets. On the other hand we have Lila, master thief, living in grey London. After Kell bring object, that shouldn't exist, from white London, he is hunted and escapes in grey London, stumbling on Lila. 
 A love the world created, it is worked out till perfection, it is logical and believable and I want to live there. 
 Another good thing, two leads, female and male are equally interesting. That is really missing from most of the books I've read lately. 
 It would be nice if the book has few 100 pages more:) 
 There a little twist and turns that keep you on your toes through the entire story. The ending was nice and made me want to know more. What will happen next? 
 Highly recommend it!