I just bought this DVD (Japanese language, with optional English subtitles) and watched it last night. It's from Kinji Fukasaku, who also directed BATTLE ROYALE.
The plot isn't very original (a non-conformist cop caught between rival Yakuza families), but the production values are excellent compared to many other movies produced in the Far East during the 1970s and the movie is pretty entertaining. I think it would be even more meaningful to someone who is knowledgeable about Japanese society (I am not) because it seems to say a lot about relationships, loyalty, crime, and justice. Check it out if you're a fan of Asian action cinema.