Somebody else said it perfectly when they were talking about this manga: "This work to me is somewhere in-between a proper manga and an artbook." As someone who mostly read manga based on art work, this manga is the most satisfying. I truly appreciate being able to stop reading for a moment and just be able to absorb the level of detail in the pencil work for clothing. Samura is truly an artist based on how he carefully drew clothing, its texture and its patterns & prints. In fact, I don't really remember too much of those distracting screentones that I would have seen in almost every other manga.
One of the best "historical" manga I've ever read (besides Vagabond). From something as simple as being able to fix your own damn flip-flops to fighting with the other senses while blind. Samura goes into details of the traditional ways that needed to be cut down, and gives these missions to several characters. Examples: Anotsu seeks to demolish sword schools that value form over function, Makie is a sword prodigy who often fell back into the confines of being a woman, Kagimura defied the orders of Seppuku to chase his final goal of killing Anotsu, Manji is an immortal ronin who serves a girl with a vengeance... and etc, so forth.
The best part of the characters is that their actions are not absolute black and white. Each character had reasons which drove them, these actions make their character relatable in some ways, if not entirely. Samura manages to create a very natural way for these characters to come to life by having them question each other's justifications for their actions. I mean, seriously, hearing Anotsu monologues each time is like music to my ears but from Rin's viewpoint, he's killing senselessly and almost shamelessly.
Character development is phenomenal. While the first few arcs focuses on Manji and Rin's sometimes-symbiotic-sometimes-chaotic relationship, it was refreshing to see the Immortality Arc which really allows Rin to shine through. Maybe her technique never improved but her strategic thinking definitely did. It was also interesting to learn that while Anotsu is so ambitious to build an empire that values function over form in swordsmanship, there was a strong disconnection between him and his men. You rarely see him around new recruits and trying to make a stand, instead, he has a very small council to help guide him through new transitions. A good example is when Manji and Rin encounters mask-maker Araya who admits that Itto-ryu swordsmen normally just try to survive because they don't meet together often.
I can go on naming examples forever to make my point for each category, but overall, I truly recommend this manga. This is one of those timeless manga that never seems to age because the artwork is so gorgeous, the plot is extraordinary, and the characters are truly unforgettable. I still find myself coming back to read this manga, beginning to end, when I cannot find a good manga to read.