Let me be specific, because there is a documented version of this complaint and it matched my own reading almost exactly. A reviewer who reread it hoping to think better of it wrote that the novel tries to pack too much plot into too short a book and lets character development fall by the wayside, and noted that the series was originally planned at far greater length before being compressed, which gives the whole middle the feel of several different novels stitched together. I felt that in my bones. Characters I liked get promoted into the main cast and then get their arcs delivered in flashback, and there were stretches where I was tracking the machinery of the plot rather than worrying about anybody in it.

What keeps it well above the line is everything around that problem. The New York Times called it a tour de force of suspenseful pacing and empathetic writing, and on the pulse level that is right: the set pieces are genuinely frightening, the humour lands, and the book is at its best when it remembers that its real subject is not the demon but the institution that keeps one in the basement. I also want to defend the ending, which a lot of readers found frustrating, because it makes a promise for the third book rather than resolving the second, and I would rather have an honest cliffhanger than a tidy one.

On audio, Fortgang and Axtell slip back into these two voices as if no time had passed, and Axtell in particular has a lot of fun with what Darlington becomes. If you have not started the series, go back to Ninth House first, because this one assumes the rules are already in your head. If you want to see the same author working with a crew instead of a loner, Six of Crows does it with more discipline.