I enjoyed it; kept me intrigued for four episodes. The cast and writing are good. Thought Richard Armitage was phenomenal, giving a raw and
emotionally intense performance as William. This was not an easy role, and he is one actor that's not afraid of taking risks (even learned German for Berlin Station).
Regarding some of the sex scenes, an obsession can make a person do crazy things (pillow love) and display abnormal behavior.
Would love to see a sequel as the final episode left a lot of unanswered questions.