I've read all the chapters I can find online - 18. There has to be more out there because there are four volumes and chapter 18 seems to be halfway through the second volume. There are also way too many plot points left unresolved for it to end where the available chapters did.
I wasn't that taken with the series, in all honesty. I feel its MAL rating is pretty much on the money. The art is nice enough - I like that there aren't ant unnaturally beautiful characters in the story - but the way mouths turn into...beaks during 'comical' moments took away from my experience; it looked weird and didn't fit in with the realistic tone of the story. I also didn't like the supporting cast besides the girl as there was no need for some, such as the bullied mangaka wannabee (he added nothing and took up too much space), to even be in the series. I'd have liked the series more if the focus had been only on the lead and his 'girlfriend'.
Talking of which, I wasn't able to really understand the lead in the first 18 chapters...or at least, I wasn't able to understand the motivations behind some of his actions. Pushing away a hot girl who happens to be into him when he's bored to death didn't strike me as a very logical action, and the reasoning behind his actions wasn't fear of rejection or the like - he just seemed to want to keep a wall up between himself and her. And as for the murder, there didn't seem to be enough reason for him to do what he did to the guy who kept turning up looking for his mother, besides his own life being **** and him wanting to do something.
I need to read the full series before I'm able to judge it. However, based on what I read, 7-7.5/10 would be fair. Nothing too special or stunning; just darker than your average story. But a story being focused on the darker side of the human mind alone doesn't make it great.