While the plot of the movie isn't exactly all that original, the cinematography is brilliant. The camera is used in such a way as to evoke a sense of disorientation. Much like what the characters are feeling.
The story is decent as far as "end of the world as we know it" stories go. I don't think it goes deep enough though. But again, this kind of adds to the feeling of confusion. You don't get all of the information because the characters don't get all of the information.
The characters are superficially cliched, but well acted. Amanda and George have some development through the movie. The others feel a little one dimensional.
It's overall, a pretty decent movie.