The plot was easily the weakest part of the film. Even in the beginning it was kind of iffy, and at the end it was just ridiculous.
However, the movie still worked for me because I cared nothing for the plot. Usually in David Mamet movies there are lots of elaborate unbelievable plot twists, so I pretty much expected the same thing here.
To me, it was a just way to put the characters in situations so the acting and dialog could come out. I liked the way the main character was played. He was interesting to me. In a lot of ways, that is pretty much what the entire movie is about, since the plot is silly and he is really the only developed character.
How did you feel about the portrayal of BJJ? I liked the realistic techniques, but the main character's attitude was definitely typical TMA through and through. Not necessarily bad TMA like a McDojo, but definitely a TMA attitude. There is a lot of "respect your sensei" vibe and laconic philosophical lessons that you just wouldn't find in even in the most traditional BJJ academy.
I mean he berates his brown belt for tapping to an arm triangle, hates competition because it's not realistic enough, and eventually his student commits seppuku to protect the "honor of the school." It made for an entertaining movie and an interesting message, but I've never seen a BJJ school that operated with that sort of philosophy.