This manga seems to have the makings of a great story, unfortunately like many others, it is overly-ambitious.
As many had also pointed out, the story shifts between the battle of "good and evil" to "nothing is truly bad nor good" way too often. So much so that the story went from "good and evil are two sides of the same coin" to never let em know your next move. When presented with plot twists after plot twists, you begin to expect it at some point. It starts to look like the author is just trying to farm philosophy points from the readers. It is quite immersion breaking really.
Overall, the premise of the story is good. The plot is just too messy, instead of focusing on fleshing out one part of the story, it tries too hard to be "deep". This is just purely my opinion though.