For me, I loved this drama. The overall story was good and I think the cast was well put together, however, there were some instances that I was not fond of that were not a big deal for me, but might be for you since once you get past those parts, it's a good drama overall (IMO). I enjoyed the comedy and thought that it was a nice balance from the heavy stuff and I'm glad to see that it was the same screenwriter for Good Manager.

Good (vagueness to avoid spoiling too much):
1) Spoiler-ish: Tae Ho. If you've watched it you will know what I'm talking about. This had me laughing my head off.
2) Vincenzo's fanclub/his Cassano Geumga family. Everyone's admiration and respect, especially from the male side characters, for Vincenzo were hilarious and cute.
3) Some side character's developments, such as Jang Han Seo's, but to juxtapose him, Choi Myung Hee who did not change for the better and stuck to her choices.
4) The line between evil and good (the grey between black vs white) that Vincenzo was, or at least, he was the lesser evil and did not try to sort everything without violence (i.e., he used violence).
5) Plenty more little things that usually relate to the comedic parts ("Casanova" and "Corn Salad"), but not that I can think of off the top of my head right now.
Bonus: Song Joong Ki's face.

Not-so-good:
1) Vincenzo came to S. Korea to escape the mafia life and such by using the gold stored in the vault, but the whole Babel thing got his way and became the main focus of the drama, which turned out fine, but to be fair, I came for the gold.
2) The tenants began searching for the gold after the homeless person told them, thus hindering Vincenzo's main task. This was honestly unnecessary and just seemed like a filler and that could've made the 20-episode drama into 16 episodes or made it 1-hour episodes instead of 1 hr and 20+ minutes.
3) Romance towards the end was somewhat unnecessary in my opinion and I realized that Hong Cha Young's presence really diminished in the last few episodes except in the finale of course, especially compared to the side characters that seemed to play a much bigger role in the whole ordeal.
4) Ahn Ki Seok (the person from the Intelligence Service Agency) made me question the credentials of working in a government intelligence agency. He was too naive and a goofball to seem like he would work in one and to be in a high position there at that.
5) There may be other parts that I was not fond of, but again I cannot think off the top of my head.

There may be scenes in the "Good" category that you disliked and scenes from the "Not-so-good" category that you do like but I found that this drama was not a waste of time, in fact, I regret not watching this sooner. So to each their own.