The story in this movie is allegory to mental disease such as dementia or Alzheimer's. Dealing with a family member that "transforms" from a person you knew your whole life into "a creature" that doesn't remember its own name IS a horror in real life. So although idea of this movie is not bad, the execution could be better. I agree with others: it is too slow and dull. And, no, it is not really a horror flick, i am sure many horror fans will agree.
I still recommend it for home viewing.
Another spoiler: the fact that they show three generations of women in the same family kind of suggest that disease is hereditary (like Alzheimer's), that is why in the end the daughter has a black spot too, meaning it will happen to her like it did to her parents.
