Horrible, if intriguing, movie. It might sound whacky to suggest, but I reckon the whole thing was both a literal presentation of stalking, but also a metaphor for stalking in real life. ie. it feels like you're going mad, that you can't escape the stalker, that you're trapped in with them, that they're there when you go to sleep at night and there again when you get up in the morning, that they're manipulating your every emotion, and that even when you 'know' that they're gone (eg. after she's killed him), you still see them wherever you go. In that regard, I think it's pretty successful. It's so damn nasty though, I couldn't recommend it. It's pretty torturous just to watch. Interesting.