Well, I suck at describing things without spoiling shit so in order not to spoil anything, my description may not be the best;
What makes this manga good is that it shows how corrupted the human system can truly be and unlike other mangas I have seen, there is no things such as ''friendship always prevails'', ''peace will always win''. In fact, the ''good'' characters have the exact same chances of dying as the ''evil'' characters so people who don't like seeing the good side always win without any loses would surely love this. The characters themselves are all enjoyable really except maybe two or three of them depending on your taste in characters.
The manga is quite dark since like I said, it represents the corruption of the human world quite well. And it's interesting to see how the ''good'' characters keep on getting closer to the root of this corruption in order to eliminate it. The power scales are nice because there is no mountain busting or such things. The main character himself is one of the few main characters that I actually like. He is no Naruto because unlike Naruto, Tatsumi (the main character) knows that he can't just become some kind of a god who can just bring peace to the world. He also knows that he will have to kill the people he is friends with if they fight for the Empire (the source of the corruption).
Anyways, that's my crappy explanation, but I don't really feel like writting a long ass essay right now so I decided to keep it a bit shorter. Over-all, this is my favorite manga and I'll definitely strongly recommend it to you. However, if by any chance you can't handle a more dark manga then I guess this isn't a manga for you.