Roman exciting policeman holding in suspense until the last page

I hesitated to buy this book for great Harry Potter fan, I was afraid of being disappointed. I should mention that after the fantasy, detective stories are my favorite genre. I did not see too how JK Rowling could pass successfully to a genre so different. For economy, I bought the audio book read by Robert Glenister. Early on, I was hooked by the pleasant writing, vivid descriptions and especially well rendered characters. Having lived in London, and many market streets, I also enjoyed the mention of its contrasting neighborhoods.
The enigma is credible, subtle clues accumulate over questions which are revealed very different personalities. Humor is also the rendezvous. I devoured the audio book, and I stayed on my hunger: one would like to know more about certain characters, in short, we would like that the book does not end!
The ending is surprising enough although early indications the hinted. Again, it is well balanced.
All good recipes of the detective novel are present: suspense, progression of the plot, good characterization of the characters, and original enough but not too unrealistic outcome.
In retrospect I think that behind the magic and fantasy, the Harry Potter series also contained all these writing qualities otherwise it would not captivate both children and adults. Congratulations and thank you to JK Rowling / Robert Galbraith: what talent!
It's good that she chose a pseudonym because the book is definitely not for children.
Besides, the only downside for me, the coarseness of some dialogs (Strike). I personally do not know anyone who uses this kind of expletive at this frequency either in English or French, and I met them only in American movies. But, hey, maybe she wanted to stand out from Harry Potter and it's not too serious.