It's OK, but really not that great. There are better survival manga out there. Still, it's relatively short so worth a look if you like this genre and have nothing better to read.
My thoughts on the story... well. I enjoyed the initial starting chapters but the majority of the story is quiet slow and boring. There are some MVP characters sprinkled throughout the series but their appearances are brief and from about chapter 26 to the rest of the story is RAPE heavy. Yes, that becomes a huge plot point from the second half of the story and although they don't show too graphic scenes... it's very uncomfortable to see whenever its there. And the ending is okay but I didn't really feel that much for the main characters in the end.
Its a series that I find bordering between decent and below average.... worth binge reading if you have the spare time.
As someone who has been on an earthquake, and has seen people going mad, this was great, totally worth the reading.
I wouldn't really say that there was something I really disliked at all, maybe just how dry some of the end felt.