It is difficult to let people know the problems I have with this movie without giving a bunch away, but let me just say that it takes a highly improbable and unexplained event (all mothers on earth somehow stop having babies at the same time), adds some vivid imagery and a few half-baked ideas, and caps it off with a set of characters that we have little or no investment with at the end. There is little sense of jeopardy here; at one point a character turns up shot, but it doesn't seem integral to the story. This is the kind of movie that would be more interesting if it was either more believable or more thrilling. Taking a far-out concept and wrapping it in a plodding mess of a plot is a recipe for disaster.
Review of Children of Men
