This has a terrific post-apocalypse setting, and excellent presentation of it and many ideas about same. Also offers truly fine, realistic drawing and characters, and good pacing.
Where I am reading in it now, though, it's morphed into the usual manga/anime Heroic Battle mode. The presentation of all this hyper-violent heroism--by soldiers who actually but unnaturally manage to stay ALIVE through their section of the manga--thoroughly undermines all the story's previous blather about how bad people killing each other is. Kind of reminds me of the prologue to World War I, where Europeans societies armed themselves to the teeth with killing machinery while telling their potential cannon fodder how great it would be to fight and die for their country.
When the whole continent finally actually went to war after almost 100 years of that, the said killing machinery slaughtered those brave young people in unbelievable numbers. Most soldiers didn't stay alive long enough to discover any Opportunities for Glorious Heroism. And the War then degenerated into a trench warfare stalemate during which similar, and worse, slaughter continued for 3 years.
After another round of similar slaughter in WWII, Europe and Japan had learned their lesson--for a while. I hope they don't forget. Popular stories of individual heroism in mechanized warfare like this, however, can gradually set us all up for another round of slaughter.