Really enjoyed both seasons, I've read the book a hand full of times and they do a really good job making it into a tv series.
Two additions I woulda enjoyed this season,
More BTK
Showing how big of a roll John Douglas or in the show holden ford had on the trial of the Atlanta Child Killer, like the fact they used a strategy to make him snap/scream in court and it flipped the juries opinion completely towards guilt