The 2 ideas that this movie
1) has nothing to do with reality and
2) was totally based on this dude who's suing the filmmakers
are mutually incompatible. They can't both be true.
I totally support this as best picture. It was the best film I saw this year, at least. Many of the criticisms miss the mark for me. I never saw the film as a documentary of the war or a training film - it's primarily a character study of a specific (reckless, danger-seeking) man. Bigelow seems to specialize in films about the psychology of thrill-seeking behavior.
SPOILER!:
Example: I've heard criticisms when the Renner character goes into the city during the night, all alone, looking for the killers of the young boy. That this was reckless, and no one would do that... Well, yeah. The entire point is that he's cracking under the pressure and acting stupidly and recklessly - and he's also deluded and misinformed (the boy is fine, the people he targets are innocent). It's very much the point that he was doing an insane thing.