That having been said, the documentary is certainly a fresh perspective on Musashi. I'm not going to comment on how accurate it is, but it's certainly a different perspective than the one espoused by most fictional narratives on Musashi, as it tries very hard to integrate real historical background in an attempt to dispel the so-called "myths" surrounding the legendary swordsman, it explains (or tries to explain) Musashi's obsession with battles.
Now, let's delve into the real important stuff (the action scenes):
Art: The art is very good, characters are well drawn and look like real men, not moeblobs. I would say the character drawings are at least equal to Shigurui in terms of quality.
Animation: Very fluid. The animation is very smooth and fluid and is easily some of the most fluid swordfighting I've seen in anime.
Choreography: Excellent. The movie actually provides examples of Musashi wielding his unconventional two-sword technique to devastating effect, how he uses one sword to parry and the other to cut, simultaneously. It's amazing.
