The first 6 episodes were really slow, even compared to "A Love so Beautiful". I'm not into watching the ugliness of society (be that Korean, or American) for extended periods of time, I was ready to drop the drama multiple times for that reason, but the entire plastic surgery thing kept me interested just long enough to reach episode 7 and then things turned for the better. I realized that I really started liking the cast & the romance was getting more and more interesting. There was no humor at all in the first half, but there were quite a few funny moments later on too. As usual in a drama like this I expected the worst from the love triangle, but that never happened, that's always a giant plus. I don't really care about bromances, but this one here was not much worse than in Goblin. I also like how it ended. Yes others have commented on how many secondary plotlines are unfinished & how great a second season would be, but I disagree. I'm genuinely afraid of what the plotline in that hypothetical second season could be. I feel that they followed the still ongoing webcomic too closely up until the ending, that's why we had all that melodramatic setup in the beginning that couldn't really lead anywhere in 16 episodes and honestly I'm not that curious about their resolution, feeling that it's better not to know, I'm content that I got the happy ending that I wanted & the topic of plastic surgery & the psychology of plastic surgery were sufficiently explored.
The OST was just there, here I am writing this 8 hours after finishing the series & I don't recall a single song, or track. Not memorable at all.