Honestly this manga is a work of art.
The art is great, the characters are great, the story / plot is outstanding.
Fantastic worldbuilding, also really great world in general. Very immersive, the characters and world just feel alive. It's probably a bit hit or miss, and i can imagine that it might not appeal to everybody, but it certainly hit me. I can't really think of more to say, it's just great in general with certain very strong points.

TL;DR: This manga achieves what it set out to do splendidly, it's generally strong in basically every aspect, and so deserves at least a 9.

With that said, it gets a 10/10 due to bias.