I am pretty sure I liked this drama more then a lot of other people. I love sci-fi dramas and so this sucked me in the moment I started watching it. But it's more towards the ending and the last episode that turns people off, but I will get into that.

The premise of the drama is more or less an apocalypse type of plot. Trying to survive these mutant things and whatever the smoke is. Like I said, the plot is really good and for the most part it is well written, but then there were a lot of plot holes. The main questions (that I had) that weren't answered were how did the smoke/mutant thing appear, out of all the people it wasn't clear why Dong Rim was chosen, why was there a specific scene that the turned/mutated Jin Seok was still looking for Dong Rim, and how the mutants all died like that. These unanswered questions could be a turn off for a lot of people. The ending even more so. It was weird how everything went back to normal. It pretty much felt rushed. But I personally liked the ending, it could've been a lot worse and not even have a good ending.

I think what made me like the drama a lot more was the casting. As much as I loved the plot, the casting was even better. I always looked forward to seeing each of the actresses and actors even if their characters were not so good or even evil. And it was nice to see a lot of old and new faces.

If you don't like dramas that don't explain everything and are not into sci-fi than I don't really recommend this drama. But if you don't mind plot holes and love this type of genre you should try give it a chance. This is a personal opinion and I since I pretty much enjoyed it I give it a 8.5/10.