Conversely if you don't like Oliver Stone movies, you aren't gonna like this either.
It's a good movie and it's good entertainment, keeping you at the edge of your seat most of the time. And as such it does deserve 9 out of 10. The reason it has a much lower rating is because people take it for more than that and disagree with it. Just take it as what it is - a work of fiction. You wouldn't rate down an episode of the X-Files because not everything it portrays is exactly that way in reality, right? So why do it with this movie?
That said, even though it's of course fiction and at best a fictionalized version of real events, it's not even a badly researched movie. They definitely did their research and it encourages you to do your own research. Basically that's the message I got from it. It encourages people not to rely on what this movie portrays or what any movie portrays for that matter, but to look at things for themselves and form their own opinion and to do that with everything, not just with the subject of the movie.