I've watched the first 2 series, assume there will be a third since it was left up in the air. Like some other reviewers I found the police behaviour a bit on the crazy side, always going off doing dangerous things with no backup, ignoring obvious clues, no strategy just always responding to the next weird thing. Also, so many killed but still only a few locals doing all the leg work? Other than a random riot squad who showed up out of nowhere and then disappeared again, I would have expected a national response. All a bit annoying.
But other than that I really enjoyed this show, the 1st series more than the 2nd which was much slower. I did fast forward through a bit of the gratuitious anxiety provoking scenes in the 2nd series, predictable outcomes.
The serial killer, not sure of the name of the actor, played such a tremendous part. He was so creepy, yet somehow increasingly likeable. Some of the actions of some of the characters just seemed a bit unbelievable. Emile's mum being the main one. But generally I enjoyed the slow reveal of characters back stories and the character development as both series progressed.
The scenery and music were wonderful. The story generally was good. The acting perfectly fine. Well worth a look, just don't get hung up on the quality, or otherwise, of the policing.