I saw Manchurian Candidate and it now ranks as one of my favorite - dare I say, it ranks as one of the best - movies of the year.
First let me say that Jonathan Demme is a freaking genius! His vision for this film was amazing. You are on edge the entire time. He uses ambient noise and camera work to portray the extreme paranoia of his characters and of these really confused, edgy political times.
The film is a remake of the amazing Frankenheimer film that featured Frank Sinatra.
Go see this movie.
As far as how it relates to Fahrenheit 9/11. Well, I guess there are 2 schools of thought. If you want to bash Bush or have trouble understanding how fiction can tell a factual story then you should stick with Michael Moore. Now, if you are the kind of person who doesn't need to be beat over the head with an idea or you recognize that fiction quite often has factual undercurrents (Sci-Fi fans really understand this concept) you will understand that this film speaks volumes and it speaks volumes that Michael Moore can't touch. Moore can say things because he has to avoid slander. Moore won't say things b/c his focus is SO narrow. In Manchurian Candidate the story can allude to all sorts of politicians and political issues and not worry because the story is "made up."
Besides, I think Demme's work is far more poetic than Michael Moore. And don't give me a line about Moore doing documentaries b/c documentaries can be very poetic, did you ever see Winged Migration or The Civil War?