I liked the first season of this show for several reasons. It was an important topic to show the partly awful circumstances in the Korean military. It's a topic that was still taboo and it was important to show the (for the show probably) worst sides of the system and what consequences it has on individuals who had to endure all of it, and what non-consequences it had on those responsible for it.
Also it had great acting from several actors, the soundtrack was good, the background story of Jung Hae-in's charcater made sense, it all climaxed in a horrible finale in the last episode of season one - great.

Soooo, as with so many formats, they smelled money when the first season was extremely successful and popular - and effed it up with the second season. Everything just goes on, the bullying starts again in the first minutes of the first epsiode of season 2, - sorry, I am not masochistic, I really do not want to watch another several episodes again seeing people being the nastiest and lowest of the low to each other - I got that message that this is an extreme problem in the Korean military, and the tragedy behind this IN FULL in the first season. I'm not into torture porn.

The story and script are getting weird and unlogical in sesaon two, time jumps back and forth, conspiracy stuff, some severe plot holes, oh, and as some icing on top at least Hae-in without a shirt - sorry, not enough.

It seems like (as in so many other cases where a first season of a show was great) that they just wanted to milk the success no matter what and the second season just lacks in every aspect.