I thought the mother was (spoiler)

a ghost of some sort for a substantial chunk of the film. Possibly the description misled me and possibly I've seen too many films recently where that would have been the case.
Anyway, doesn't matter, it's a really enjoyable if actually quite dark and seemingly unstructured film. I only have one sort of complaint and it's a very silly one - Penelope Cruz is too beautiful. It makes it seem ridiculous that anyone would ever give her a hard time.