On it's surface the plot is a basic anime revenge story but it's told in really mature way. The characters are some of the deepest most will developed characters I've ever seen in ( the first season) an anime. It's also probably the most feminist (action) anime I've watched. It deals heavily with the place of women in feudal Japan and the women navigating it are great complex characters. The other main character is a disabled guy who while funny isn't played for jokes and is incredibly resourceful.
My only complaint with the show is sometimes the art is a little weird and there's a couple of scenes where the plot armor is a little heavy. Seriously give it a watch.
About midway through, when they get into the main character's backstory by cutting between her actual life and a shadow puppet play of an old Japanese parable, you really see the show's artistry shine. The show's core narrative is rock solid. The animation is superb. The characters are genuinely fun to root for and the twists in the plot keep you engaged. Heroes and villains and bystanders alike all have a compelling role to play.
If I could make one change, it would be to soften some of the more unbelievable stunts the main character manages to accomplish. There are definitely moments that stretch credulity, bleeding over into Shōnen anime. But its not out of line with your Cowboys Bebop or Samurais Afro or Champloo, so I'll bite my tongue.
Oh yeah the shadow puppet episode was great story telling. In general i did like the art, there were just a few frames every now and then where it looked like Borderlands.