It's too bad he never competed professionally. Staged demonstrations don't impress me, and some of his more obessive fans are neurotic or outright liars. For example, they claim he was a street fighter. First of all, there's no evidence of that, second, a martial artist like Bruce Lee would (or should) never engage in street fighting, third, of course a black belt is going to win street fights. Others claim he would knock out any top MMA fighter with one punch, no matter the weight difference.
Did he have discipline, will, and intelligence? Yes. Did he develop a new martial art? Yes. Was he the greatest martial artist and fighter to ever live? We will never know.