The premise of this story is so utterly ridiculous, that you rapidly appreciate that it can go in any direction. Whatever the writers choose to pursue as the actual tale, is entirely their right.
What they do pursue, is a tense little drama based around the situation that the magic creates. The result is a dark, edgy, occasionally morbid fairy tale - one could argue that all fairy tales are like that anyway.
Mads gives his usual beautiful-teak performance (I'm sure the man has more than one act... then again, I don't really care if he does), and the supporting cast, particularly the wife and daughter, are excellent.
I did like the way the story gets on top of you, and accelerates. There is a story by Charles Stross that this movie reminds me of, but I can't give you the name without spoiling (it's also not one of his better tales I'm afraid).
Where I could possibly knock off points would be maybe in the logic, but then this isn't an SF tale, it's fantasy. It's also a little long for the tale it tells, it could have been just a bit more compressed for the content. Finally, it's just not a work that moved me - it's good, it's gripping, it's entertaining. But it's not high art.
I can recommend this film, just don't expect it to blow your mind.