I liked Children of Men and also didn't. I'm fell in love with the PD James novel years ago, but despite that, the book has a very slow start, and in the film they skipped over that snore-fest. However, the film also skipped over what I thought was the real flavor of the book; the little details about how the infertility was affecting society. There was a great scene in the novel of women pushing dolls in baby carriages and a priest having a meltdown when a deer walked into the church (because animals were not affected and it was all going to be theirs soon enough), and we saw none of that.