If I had to summarise this season I'll have to say "it's pain and suffering".
This season was perfect, the suspense and anxiety it makes you have are priceless. I believe Atsushi didn't have much protagonism; nevertheless, it didn't bother me. I also loved the way they explain some characters in more detail, such as Kenji.
In every episode they play with your feelings, things don't how as planned most of the time. There are parts, which could be seen as predictable, but I believe they compensate having characters such as Fyodor or Dazai, you never know what's gonna happen with them. A highlight for this season, for me, would be the interaction those two had, it was amazing (altho I do think there are parts in the manga that would have been refreshing if they had been animated).
I think the ending leaves a lot of questions, I honestly believe there were things that didn't have an explanation; still, they will hopefully explain it in the next season. I really recommend it if you like not knowing what's gonna happen next and if you like watching the main characters struggle, this season definitely made the script seem as if it was against the "good ones"