Lets start with the art on this one. The art is confusing and looks like rough sketches with marker shading, especially in the beginning chapters. A lot of pages feel like partial rough sketches with unfinished parts. Want to see what the abyss looks like? Nope, you’ll get very little clear shots of it(if any). Most of the time, the abyss will be undetailed/foggy/unclear/rough sketch like. No majestic scenery a la Berserk or Kingdom here. Also, the facial expressions on some characters are really unimaginative/1 dimensional. The art does get better in the latter chapters, still confusing and unclear but better.
Now the story. Its like a story for kids, complete with overly simplified plots, Generic 1 dimensional lifeless villains and cutesy wootsy stuff all over. Looking for complex plot or characters? You in the wrong place buddy. The twist in this story, is that it brings out MATURE content every once in a while, making a nice contrast with the cutesy wootsy stuff (some of it is just PERVERTED tough). The exciting, mysterious, imagination provoking abyss is what really carries this story. As a double edge sword though, the abyss also gives the author too much freedom so sometimes important events seem meaningless.
If you like cutesy wootsy stuff and 7 year olds save the world type stories but want one with a mature content twist, then you are probably going to like this one. NOT so much as mature, just MATURE CONTENT.