I have not seen more than five of the classic (and undeniably classy) Zatoichi samurai films, but this is surely the best, cinematographically, so far. It;s hard to believe this was shot in Eastman Color, a kind of poor second to Technicolor (and with far less durability; either the negative was especially preserved, or digital restoration was performed by a true expert; but in any event, this film is absolutely gorgeous to look at.
The story is dark, as others have noted; but the Zatoichi series, like most of the sword-fight genre series films to come out of Japan, is pretty heavy-handed stuff; the Japanese seem to take this sort of thing very seriously. Yet there is no doubt Zatoichi "24" stands out as exceptional, from both the series and its genre. The reason, I think, is its almost total sense of social dislocation; Zatoichi is treated by the other characters as somehow less than human, and his determination to fight at the end somewhat more than human, and so he comes across as something other than human; but the other humans of the film come across as rather poor representatives of the species. I should note that there is very little dialog in this film, particularly at the most dramatic moments, which heightens our sense that we are watching some tragedy from another reality.
The question here is, has director/star Katsu pushed his character to such an extreme that he is no longer representative of his genre, but somehow an independent dramatic entity, a "grade-A film", as might be enjoyed by those who disdain genre-films? well, I suggest this film to such viewers, as the "one chambara (Japanese sword-fight)film to see". But in any event, it is an exceptional, and troubling, cinema experience for anyone.