Severely underrated manga both in the ratings and in these comments.
The premise of this manga could easily have finished up as a one-shot, or perhaps something very short. Instead, by expanding the plot several times, and through a masterful exploration of existential anguish and the struggles in relationships, this became a really thoughtful and moving manga. Anyone who has been in more than a couple serious relationships should be able to relate to some of the experiences here, even though they've obviously been dialed up to 11 and painted in terms of murder.
I would also like to say that, unlike many manga, I was really emotionally invested with many of the characters here. Really I think the exceptions to this were mainly a couple added towards the end.
It is true, this manga is not perfect, but many people here are exaggerating the flaws. For example...
Was the ending rushed? Yes, it clearly was. However, unlike many other manga (there seem to be a lot) that rush in the end, the author clearly had an idea where he was going. I believe he just had to tell his story in a rather abridged fashion. The themes still ring true, and the ending (after some non-sense in the final arc) actually was really quite beautiful.
Was the last arc (roughly last 1/3 of the manga) horrible? Not horrible, but much more flawed than the first 2/3 certainly. Again, the author packed new characters, new struggles, and some big twists / revelations into probably 1/2 of the space he would have wanted for them. However, I think at least some of the themes still connect, and if you think about it, it's not as nonsensical as some others make it out to be.
Were the final chapters shorter? No. Each chapter was short compared to many manga out there, and I believe the length was consistent pretty much.
Was this shallow / edgy / random / etc? No. The author clearly had questions, ideas, and themes he was working with beginning to end. As noted before, while the situations and behaviors of the characters were extreme, they did follow from valid philosophical questions and social and emotional struggles that people face in relationships and/or in society. Despite this, for people that have been in serious relationships, or who have struggled with these kinds of questions, it is easy to recognize situations where one struggles to fit in, or awkwardly navigates the early stages of a relationship, or struggles with possibly growing apart from a partner.
This has to get somewhere between an 8 and a 9 for me. I would probably be giving it a 10 if it were not for the rushed final arc / ending and all that entailed. However, again, I have seen MUCH worse rushed endings, with much more severe ass pulls by the author. That's just not the case here. As rushes go, this was done the best that could be expected.