I've read a few darker mangas, but this one is the most unique and (to an extent) the most realistic.
The story has good pacing and does a good job of making most of the characters flushed out. The final twist was somewhat unexpected, but also made enough sense that it didn't feel out of place; a relatively hard thing to perfect when telling a story. The ending was also an average bittersweet one.
The art was somewhat basic, with the exception of a few scenes having some more detail. However, considering the genre I was reading, it was something that I expected.
Most of the characters were well written. The author did a great job at handling their placement, thoughts, and emotion in the story. I would only consider two characters to be sub-par, characters with somewhat poorly written motivates and are only there to cause problems.
Even with the small number of problems, I really enjoyed reading this. I think it was written well, and did a great job of handling heavy topics like murder and rape. The ending was somewhat average, but I get the sense that it was intentional. It wasn't meant to be anything grand or minuscule, just average.