this would have made a very good Bruce Lee movie, but as a Jackie Chan vehicle it's adequate at best.
there are some good fights in here, and one cool one done on roller skates (Jackie was taught by one of my coaches, John Hall, who is credited in the movie but not in imDb, how does one change that?).
however, Jackie plays a Korean, who enters a big brawl to win $15,000 to send to his brother's clinic in Chicago. it's an interesting version of the "tournament" martial arts movie, but the choreographers are stuck in the 1970s a la "Enter the Dragon (1973)" and have Jackie do many similar moves, instead of his completely different style that we are so used to these days.
so the fights look a bit slow, which didn't blow US audiences away in 1980. what I found more interesting was Jackie was given a love interest and looked good as a romantic lead. that was very cool.
it's definitely worth a viewing, but it's pretty easy to see why it failed at the BO back then.