Well, I enjoyed it, giving it 8/10 without regrets.
The concept was interesting even if not used ideally.
We saw some character growth and most characters actually acted their age, which is not something that often happens in manga...
If we go on onto negative sides... Kiriyama being too way above human level to be taken seriously..
Too much Shuuya 'no killing' even when faced to death of the loved one.. realy.. took him so long to shoot the guy, all chances were there on noriko dying unless we count plot armor, lol..
I must agree with most above, who mention that out of all character stories, Mimura's was certainly one of the most engaging, and it went downhill after that pretty much.
Both Sugimura and Mitsuko vs Kiriyama was simply full of crap.. Ok, I can take Mitsuko being defeated so easily, although I expected it to still be more interesting..
But seriously - Sugimura losing it in close fight.. I wouldn't mind, if he was at least forced to sacrifice himself as shield for his girl.. but nothing like that, she never was a big issue in a fight, they fought pretty fairly 1vs1 big time and Kiriyama kind never even recieved serious physical wounds, while sugimura easily lost his eye and fingers.. The reasons mentioning it, even though stupid, fine, even if he is stronger, a defeat is fine, but seriously - after flying up the air after strike and acting like nothing happened.. well, there should have been some real consequences on such fight.
But then again let's not forget he survived the bomb from mim... lots of issues with manga, so I will stop it at that and simply tell that despite all the bad sides, it's enjoyable enough to close my eyes on most of them.