This is going to be a fairly short review. So, what do I think of, Children of Men? It's, meh. Fairly average. Here's why.
Acting: No on impresses here. Clive Owen, Michael Caine, Pam Ferris, Julianne Moore (for the small time she's in it), Chiwetel Ejiofor as well as Clare-Hope Ashitey. Everyone is very average in the film. No one delivers a single performance that leaves a mark. Neither benefits or takes away anything from the story.
While the premise itself is very interesting and being based off of the book, I now officially have no interest in the book after seeing this film. I hope the book is better cause there isn't a single moment of this film that leaves an impact or a single emotion. It doesn't make you feel for the characters nor the situation of the story.
Alfonso Cuaron: This man is the biggest reason I decided to watch this movie, because people on this site praise this man and kept pushing for me to watch it. So, I finally did. This man is not who many think him to be. He's a very average director who creates a dull film (although, it's not exactly a fairy tale story) with average to bland performances from the actors. To be honest, this film makes me enjoy and appreciate Harry Potter and the Prisoner of Azkaban a bit more. Not for the right reasons either. I don't understand the praise this guy gets. His films are amazing to watch from a visual enjoyment and the cinematography is amazing. He doesn't overall direct all that good.
Final thoughts: This would've been a longer review but there isn't much reason for me to continue. Children of Men proves that Alfonso Cuaron isn't a good director and makes very average films. He doesn't bring the best out of his actors as this film clearly shows and the premise does not live up to it's potential. As a drama, it doesn't work. Unlike what rottentomatoes would have you believe, this film doesn't work on every level. While as a political film, it's okay. Not much. I wouldn't advise this film for anyone who hasn't seen it cause it's a hour and forty nine minutes of almost everything possible in film on an average level. Very bland piece of film making.