One of the best manga for writers to learn about themes, because there's so much of them here. The road to sucess, what it means to be a man, lessons about humility, what a strong person truly is, etc.

Musashi is an outstanding protagonist, you can pinpoint every reason for everything he does through his backstory. He's proactive, a loner, a violent and angry, but scared man, and there's all a reason for it. Vagabound adresses a pretty entertaining question, too: what if the protagonists dreams are just wrong?

The manga can teach you a lot about life, but it just doesn't stay on philosophy and character writing: the fights and conflicts are very suspenseful, the manga isn't scared of making Musashi look weak. He loses fights, he gets beaten to an inch of his life, and he even steps on a nail while walking! But he gets through everything, and not only by getting physically stronger. He learns a lot about life, and that reflects on how he uses his sword. Musashis's mind gets stronger with him, and the manga does such a good job at tying this journey about personal growth to it's characters and it's fights.

It's a must read if you like self contained and very personal stories about a complex character continually evolving and learning.