I think far too many people are going into this film thinking it's a supernatural theme - it really isn't. I thought it would be as well (based off of the DVD case description) and I was pleasantly surprised to find that I was wrong about that when the final credits rolled.

Ultimately, this movie is a study of the effects of guilt on the human psyche and how our fears can ultimately consume us. Paying close attention to the movie is required to fully unravel the twist ending. If you're not watching it (or rewatching it) carefully, most likely you will miss out on important clues and end up disliking the movie. I thought the cast did an incredible job of being believable, especially Marisa who fluctuated beautifully between sanity and fantasy.

Is this the best movie I've ever seen? No... but I would recommend it to anyone who likes to be surprised.

One bit of advice for those people reading this review after watching the movie and not understanding it: go back and look >closely<, this time, to the items in the shopping cart at the end. Quite a few puzzle pieces that you need to put together to understand the twist are laid out perfectly for you.