I like the protagonist. He's cold, hard, and pragmatic---all nice and good things a cold-blooded detective should have and all that.
I like the other characters somewhat. They're interesting and realistic(as realistic as characters can be, i suppose, in cop dramas like these).
But I think the telling of the story lacks something. Sure, it gets somewhat violent, and sure, everyone has something horrible to show, but I'm not feeling moved. Some moments are just over dramatized; at some points, I just want to burst out laughing.
I'm not feeling slightly horrified, as I did MPD Psycho, or even feeling surprised or shocked. I think ALIVE! did a much better job shocking me than this one, though I can't say that I liked that one much better than Jiraishin.
And there was the art. Normally, I don't care too much about the art, as long as the storyline is great, but the art just repels me. Maybe it's supposed to look off-center and deformed-ish, maybe it's to fit the plot line, but whatever it is, as a reader, it repels me.
All in all, I have to say I'm not too interested in continuing this manga. Maybe I might pick it up again and give it a chance(maybe when the Diablo part comes out), but I think I'm going to give this manga a pass for now.
Note: This is my opinion only. Don't take it too seriously.