Loved The Alienist. Truly intriguing plotting. The whole concept of of spiralling deeper and deeper into the mind of a killer (a la a 19th-century FBI profiler) - and thus into the equally shadowy and mysterious mean streets of New York - is brilliant. The characters were unique and funny and I was more than willing to follow wherever they led. (Which means some pretty gross scenes, towards the end.)

But...I signed on for a psychological thriller, not a history lesson. Carr gets so caught up in various NYC landmarks and their architecture that by the time the book ended I was cross-eyed trying to sort out relevant clue from historical digression.
So during a recent rereading, I skipped past the digressions entirely and just focussed on the plot, and had a much more satisfying reading experience.