So...How is this movie a 'Masterpiece'?

Lady Snowblood was recommended to me by a few people after expressing my love for the Lone Wolf and Cub series. I decided to check it out and looked at the IMDB message board, where numerous people praised Lady Snowblood as being a "masterpiece", so I was rather curious to see it. Luckily, my school had a copy in the library and so I watched it last night for the first time. I honestly don't understand what it is about this movie that makes it "masterpiece." While I believe some of the direction was rather interesting, with some against-the-norm camera shots, there was really nothing in this film that stood out in any way. Can anyone explain in a bit more detail what they thought was outstanding about this film?