Unlike other versions of this story that I have seen (and I've seen at least 3 or 4 others), this one begins well AFTER much of the plot has passed and so much explanatory exposition occurs in the first 20 minutes of the film. Then, when the film flashes back 20 months, it STILL goes back to AFTER the important events have occurred (when an official tried to kill one of the Shogun's trusted men). So is the 1994 version of "The 47 Ronin"--a completely non-sequential version of the story is told.
The 47 Ronin is a classic Japanese story, and I assume that practically every adult in the country is very familiar with the story. So, for a Japanese audience, this version of the story would probably work great. However, for those NOT familiar with the story, it's very confusing and told in a very roundabout manner and is quite confusing. Because there must be about a dozen other versions out there, I say try them first. Though, try also to avoid the recent Keanu Reeves version simply because it's pretty stupid.
