I watched this movie because the idea was intriguing. I felt right away that it wasn't going to have much of an ending; it's not really the sort of story that would ever have a solid ending, unless it was an episode of the Twilight Zone, which it clearly was not meant to be.
So I can accept the weak ending, and I'll even accept the analysis of one of the user reviewers here, Richard Burke (or was it Robert) whose analysis struck me as completely reasonable and well though out, and thus accept that the movie more-or-less makes sense.
The problem is, this is a really boring movie. I don't know what the people who talk about it being "suspenseful" are thinking, because this movie moves like grass growing. It is so slow that after the first half hour, I put it on fast forward (the advantage of subtitles is you can watch a movie like that). Even at double the ordinary speed, it was still slow moving.