This is a criminally underrated manga and I'm not completely sure why. My guess would be that people don't like the art style, which is fair enough, but that's such a surface level criticism that I find hard to take seriously. I read another manga recently called Ningen Tokei, and although it isn't great, it still has its merits. Yet it has a 5.10 on MAL, just because of the art style.
I think anime and manga fans are a little spoiled. But I digress.
What makes this manga great? For one it is constantly engaging and exciting, its devilishly hilarious because of its dark
and twisted sense of humor. Plus it just works as an over-the-top crime thriller. It's the kind of thing that Tarantino or the Coen Brother's would come up with if asked to write a manga.
Don't let the art or the low score scare you away, this one is a hilarious thrill-ride.