I've been avoiding this thread as I was watching the episodes on a bit of a delay, but now I've watched them all, so it's posting time!
*SPOILERS AHEAD*
So, my first-episode stab-in-the-dark guess for who the villain was was Stoffer. By episode 6, I was convinced it was Karen. I thought it would be a good twist to have the abuser be a woman, and having Karen's car be on the list of car numberplates they were looking at (the printed-out one, with the owners' names given) felt like a good clue. I kept hoping it was her until it became clear towards the end of the final episode that they weren't going down that route.
I liked the ending. Lund was the only person[SUP]
*[/SUP] who wasn't going to forget about the victim, and she kept her promise to Loke that the murderer would be punished. I'm so glad they didn't have her kill herself afterwards. That she's going to go off and try to find out what happened to the other victims felt true to her character (although I'm not sure how she knew that there were others, before the conversation in the car with Reinhardt). It's a mad quest for justice, but that's what Sarah Lund does.
[SUP]
*[/SUP] I liked that Karen also wanted to get the truth out. Politicians in each of the three series seem doomed to give in to corruption, even if they try hard not to, and it was good to see at least one person in their camp who didn't put power first. I'm guessing that the writer wanted to leave one candle of hope burning for Danish politics.