The one punch man opening is nice. Personally, I like Samurai Champloo's opening . I thought it was so cool of them to use such classy tunes. The music in the entire series is amazing and the anime is worth watching just for the songs. It's awesome!
Donnie Yen is a master in his own right. Took this from Wiki:
Near the end of 2007, Yen added a new martial arts system to his arsenal. He was offered the role of Wing Chun grandmaster and Bruce Lee's mentor, Ip Man, in a 2008 film named after the grandmaster. He worked hard and studied Wing Chun under Ip Man's eldest son, Ip Chun for 9 months before tackling the role. Ip Chun has since praised Yen for his effort, and complimented that Yen is a great martial artist and a fast learner, and has managed to grasp the full concept of Wing Chun much faster than anyone else he has taught.