As a 30 years martial arts veteran, with the first 20 years being a competitor and coach in Europe, I am somewhat familiar with the American style of the business of martial arts and hence there were little remarks that I found even funnier than people without that background.
The slow pacing and coloring almost reminded me of some Woody Allen movies, but this one had it's own distinct flavor.
The more the movie grew absurd, the more grew Casey (Eisenberg) into the role, into the extreme... and all escalated.
I have found this movie very entertaining, but was missing some faster paced action, etc., but on its own, as a dark comedy, I enjoyed that movie and it some clever twists.
It's not one of those escapist movies that you can watch several times and you will find something new... I even don't know if I can recommend the movie to other people, except with a disclaimer, maybe... but again... I left the theater was was well entertained!