All you need to know is that this is a revenge manga focused on violence and occasional gore. I'd call it "revenge porn", but that happens to have a slightly different meaning. Revenge gorn, maybe?

In those kinds of works, the protagonist gets an excuse to exact revenge on his enemies, and goes full villain while doing so, and they often include violence, mutilation, sexual violence, and so on. Haven't been a lot of sexual violence in this one, though. Another work of this type is "Kaifuku Jutsushi no Yarinaoshi" which is as bad as this one if not worse.

Anyway, the "hero" is nuts, the enemies are nuts, everybody is disgusting creature, and at the same time the author wastes ton of time providing explanation why this brutal action by the villain protagonist is totally justified. So you have a rampaging villain ex-hero protagonist destroying things and killing people while being a total lunatic about it.

Breakdown:

Story: 2/10
Cheap excuse to have a protagonist slaughter thing, basically. Betrayed hero going berserk on his enemies. The enemies are portrayed as disgusting enemies just so you won't feel sorry for them.

Art: 6/10.
From what I remember it actually isn't bad, and quite skillfully done, albeit not breathaking.

Character: 2/10.
Poor characterization through and through. Characters exist to die and get killed by the hero, or to be tortured by the hero, and the hero is totally bonker himself. None are realistically portrayed.

ENjoyment: 2/10.
Revenge gore porn isn't my thing, and usually I'd want an actual story to enjoy a manga.

Overall: 3/10.
Not recommended. Unless revenge mangas happen to be your thing. Even in this case I'm unsure about this one.