(Sorry if this isn't formatted well, I'm new to writing reviews)
Fist of the North Star is an absolutely fantastic series, with an interesting cast and unique fighting styles. The action is epic, with hero Kenshiro stomping down hordes of thugs with his bares hands (And sometimes nun-chucks) with the much imitated Hokuto Shinken. But that's not why I love it. I love this series' HEART.
Despite it's Post Apocalyptic setting (heavily inspired by Mad Max, at least at first) Fist of the North Star is surprisingly idealistic, with the message that man kind is fundamentally good at it's core, and that any man can be a hero. The hero followed in the Story is Kenshiro, a bad ass of epic proportions, who is in many ways the Ideal Hero archetype. But despite his power and brutal way of dealing justice, Kenshiro feels nothing but love for his fellow man, and is always willing to risk his life for anyone who needs him, whether he knows them or not.
The (main) villain is Raoh, Kenshiro's brother. In many ways, Raoh is his opposite. He desires peace like Kenshiro, but will attain it through violence and fear rather than love. This is the main dilemma of the story, Love vs Fear and Order vs Peace.
In the end, Kenshiro is the stronger, not because he's the better fighter, but because he's the better MAN. He knows pain and loss, and with that has attain the true power of Hokuto Shinken. Kenshiro's love and sadness are literally transformed into power, while Raoh has cast love aside, weakening him. In their climactic battle, Raoh loses in the end because no matter powerful his fist was, he could never crush Kenshiro's heart.
But, sadly, all the greatest works often have the most serious flaws. The one that will be most immediate the viewer (And so PAINFULLY indicative of the time the series is written) is the sexism. Mamiya, the only real female combatant, is portrayed as competent, but NEVER as powerful as her male counterparts. (In fact, one character LITERALLY says that as a woman, she is not fit for battle.) Thankfully, the series has no problem portraying women as strong in character, but that only softens the blow somewhat.
The other main problem is that the series quality takes a serious nose dive in quality after the Raoh arc. It reads more like a derivative clone of Fist of the North star than the epic series before.