Finally finished this over the weekend - I was rationing myself to one per evening, as I felt it needed to be digested slowly rather than binged. I thought it was outstanding, and more than lived up to my prior high expectations.
The first thing it got right was in the casting, which was uniformly excellent. I had no idea that the guy who sings the cheerily playful King George songs on the Hamilton soundtrack could be so convincing as an idealistic, quizzical FBI agent. Groff played the guy who blurs the line between questioning the sociopath, and befriending the sociopath so well; he's the embodiment of the Nietzschean thing of 'whoever fights monsters should be careful lest he become a monster in the process'.
The actor playing Bill Tench was also excellent, as was Anna Torv.
But holy shit did they knock it out of the park in the casting of the serial killers. The guy playing Ed Kemper was just electric, and Brudos was also creepy as fuck.
I liked that it was very episodic - it didn't try to be a ten-hour movie, and didn't resort to a Killer-of-the-Week storyline. Too many Netflix shows don't define episodes very well - probably because they're almost designed to be binged.
You could empathise with the agents even as you knew they were stepping over boundaries as they were literally making up the science as they went along.
Visually, it was stunning, and the period details looked very convincing, as you'd expect from a Fincher-led series.
Best show of 2017 for me.