I read this awhile ago and plan on re-reading it one day but I have to say, this manga is brilliant. My favorite thing this manga does are the flashbacks. Nearly every character gets one. Yes it may sound really tedious but the way this manga does it is really emotional and you really feel for the characters, even the antagonists. I highly recommend giving this a go.
Extra note: There is a..... "sequel" of sorts but its done by another artist, involves different characters and the story is completely different/bad, you're better off skipping it.