*Spoiler Free *
I really really loved this movie. I definitely understand how its not for everybody, but I'm in the camp that didn't mind the lack of explanation. I think the concept is full enough that an explanation isn't necessary or a cop out. If you're worried about wasting your time with it, just watch the first half of the movie. If you didn't like it, you probably wont like the rest, but if you did, keep watching, it might end up being one you like! Don't trust the reviews. If it's been one that you've been interested in watching but have been put off by the feedback, see for yourself :)