Using my personal rating system of "loved," "liked," "meh," & "nah," this was mostly a “liked”.

Things I liked:
I started watching this for Lee Soo Hyuk and this is one of the few that he’s been in I could actually finish (see my review on ‘Scholar Who Walks the Night’; I’m not criticizing LSH, just rarely finish a drama he’s in). I enjoyed LSH in this. He does stoic bad@$$ very well—but his character also had range and we got to see him happy and sad as well. I liked all the characters, I liked their complexity, I liked their back stories. I like that they took on mental health and suicide—though it is also what made it hard to watch at times. Like most probably, I like the idea of an afterlife where we are rewarded for good and punished for evil.

Things I did not like so much:
Mental health and suicide are not a ‘one and done’ thing. For example, an eating disorder is a lifelong struggle and that episode made it seem like something that got fixed almost instantly. Sometimes I fast forwarded just because the content was triggering.

Honestly, I found myself more interested in the back stories than the stories of the people they were trying to save and often fast-forwarded until we got to back story again. I did not quite get why suicide was treated by that version of the afterlife as something worthy of hell—that seems more consistent with the Judeo-Christian tradition (please correct me if I am wrong if you know more about Buddhism or Confucianism). Especially during the era/country when/where Goo Ryun died, suicide was encouraged and expected of widows and women who had been assaulted (at least that is the impression I get, so please correct me if you understand that history/cultural era better).

Minor point of dislike: The actor they chose to play an adolescent PJG could not have been farther apart in looks and build that his 'supposed' adult self. At that age, LSH could not have weighed more than 100 pounds and that kid looks like he has more muscle than the adult PJG he's supposed to be the younger version of. I get that it is hard to get that right and I'm on the fence about whether I prefer the older actors trying to play their own younger selves or just getting younger actors to do it instead (especially when its adolescents who look so much more like their adult selves than kids do).

I kind of wish there would have been more of a resolution between Park Joong Gil and Goo Ryun. Their ending was a bit ambiguous. You can tell that Choi Joon Woong will eventually get together with his girl since it showed their strings connected, but I wish we could have known what would happen between PJG and GR.

Conclusion:
I don’t know how to think about this one. There were times I sincerely cried, there were things I simply could not watch, there were things I thought were misrepresented and could have been done better. There were also things I enjoyed. If you’re a major LSH fan, I’d recommended it. He does well and looks well in this.