in short:
this was not a season 2 following up a very good season 1 of this show.

-they kept the original characters just as a strange framework on the edges, instead about 40 new characters were introduced, none of I cared for at all.

-it seemed like they writers sat together just making up ever new gruesome scenes ( oh oh, and let's do some kind of a zombi bride, we haven't done that, let's add to too!!)

-no real storyline, instead lots of torture porn (with what is going on in the real world? I really don't want to see little toddlers being hunted with bows and being shot in the back - just NO! Unnecessary for the story and just to show crass content for the sake of it)

-almost nothing of the actual main character Song Kang? He is not really in that show, oh except for these few porn-leaning scenes fighting bare'backed' and soaked in blood in slow motion.

-the only original character that had more screen time was Eun-yu. Character development: zero. She is just running around looking broody and cold and kind of like a knock-off tomb raider. I also didn't really get why so much of the storyline was hung up on her desperately wanting to find her brother- the same brother she actually hated through all season one and as they were siblings not even remotely close anyways. And now she suddenly risks her life and that of others to find him, or what is left of him. Didn't make much sense to me.

result: I'll stick with the brilliant season 1,and I certainly won't watch season 3, as there is no way to make a sensible storyline of the mess that was supposed to be a season 2.