This is the archetypal samurai story, from the novel "Musashi" by Eiji Yoshikawa, based on the real-life 17th Century swordsman and warrior. Starring Toshiro Mifune as Miyamoto Musashi (aka Takezo Shimmen).
It is one of my favorite stories in the world and is not just entertaining, but instructional - not just about the samurai and Japan, but about the complex and stern discipline of the warrior - bushido - the spiritual discipline that Musashi himself was the master of.
Having said that, these films are not really as good as some of their contemporaries. I was disappointed. One problem is in the editing. So many of the cuts between scenes are poorly done or weirdly faded in and out that it is disconcerting to watch. The cinematography is not top-notch - lots of shaky camera moves.
But my biggest problem was with the script. Much of the narrative in the novel is about Musashi's experiences with the various teachers who shape his beliefs and values - his spiritual education is not just that of the sword, but also the potter's wheel and the brush. The films pretty much eliminate all of that in favor of pursuing the love triangle between Musashi, Otsu and Akemi - much less interesting stuff as far as I'm concerned.
And then there is the quality issue - these films need restoring BAD. The prints Criterion used for this transfer are badly faded and, in some places, badly scratched. You can see the cigarette burns clearly through most of the first two films and the third has some sections with such bad scratches that it looks like snow. A number of scenes have "virtual" subtitles - they go by so fast you can't actually see the subtitles unless you go back and freeze-frame.
Mifune is solid and stoic, but it isn't his best acting job by a long shot.