Bruce Lee is only really in like one scene. He talks shit and then catches an L from Brad Pitt's character. It's only in there to show how Pitt's character had a dark side and combat training to go with it. Without spoiling, it becomes REALLY important to the movie at the climax.

At the same time yeah Bruce Lee comes off as an arrogant and all show. I didn't like that portrayal, but there was so much else to enjoy about the film that it wasn't a dealbreaker. And considering how much the movie fucks around with history and past Hollywood icons, it wasn't that big a deal.