I don’t care what people say. I love J.K. Rowling. [This was written before she came out as a transphobic TERF and bully. I no longer support her in anyway.]
She is a skilled story-teller and talented writer. With the two types of reactions most people have when they hear her name, it’s easy to see why she wanted her name kept far from her works as Robert Galbraith. Unfortunately, this didn’t happen, but this was a bonus for those of us who would never have discovered them.
On one side, you have those with visceral negative reactions to her and her writing. (A lot of the time by those who’ve never read her books.) And on the other side, you have the people who adore them solely because it’s J.K. Rowling; Obviously. Thankfully, I’m somewhere in the middle. I can both appreciate her as an evolving writer and find fault in her skills as a story-teller, especially in her post Harry Potter novels. (I’m still waiting for the, hmm Harry Potter isn’t as wondrous as I first thought it was moment, but it still hasn’t happened.)
I know I say this regularly, but I can’t do justice to this book in my response. The more I think about it (I finished reading it last Wednesday), the more I realize I don’t know how to talk about it.
Give me a book about a another book (missing, newly discovered, controversial, etc.) and I am happy. The writing could even be mediocre (this one was better than mediocre) and I can still deal with it!
If it weren’t for the strength of the last book and Colfer’s series in general, the opening line of this novel might’ve made me turn back! I originally requested a copy of this from the publisher and 
It is very rare that a second novel, let alone a middle novel in a trilogy, can surpass the first. In this case, not only has Shepherd done it, she’s surpassed an incredibly well written debut novel with an even more creative, intense and harrowing follow-up. It is NOT a place holder as many middle books are in trilogies and I was incredibly impressed.