I watched about 4 episodes of this months ago - maybe a year - and abandoned it. I could not get into the story of a cold and mildly nutty bloke living next to a recently widowed mother of twins, who were sweet but annoyingly shouty and up to mischief, and she herself was apparently irritatingly naive and a bit hopeless. I struggled through 3 or 4 eps and then jumped ship.
I returned despite a few reservations, and didn't bother trying to rewatch the start. Quite frankly I would not have been surprised if I still found it unwatchable. However, it seems that it was pretty much just at THIS point that things actually started happening and some of the earlier irritations were at least partially explained, or faded more or less completely.
This time around, a few things fell into place and I found it fanciful but enjoyable. I began to get to know each of the varied characters slightly better and some of the irritating things stopped happening or became understandable. The nosey neighbours who appeared so intrusive and judgemental were revealed as real friends, willing to be vulnerable and reveal their secrets or follies to console each other, but also to take real risks for each other.
I can't say the denouement and the revelation of the real dark master behind all the horrid stuff came as any surprise, but that really did not matter at all, and I admit that the identity of the other "man in the shadows" was no surprise either. Well, what I MEAN is that I recognised the actor from his vice, his hands, and a very dark and shadowy quarter silhouette of him that read more like a line drawing of simply the edge of his face simply confirmed it. Smug little me. On both counts.
The FL continued to be a bit irritating at times, a bit clueless even though she proves herself to be full of courage and determination, and much more capable than she at first seems. It is a dislike of mine in dramas, to see women who are home-makers and mothers portrayed as inept in the wider world, and needing a man in order to function. And yet, despite the growth of this character, her normal demeanour remains much as it was early in the series. She did, thankfully, become more likable , most of the time.
The ML is, well, lovely. He thaws completely, and warms those around him, becoming friends even with the King's Castle Mafia - such is how I think of them. The way that all his relationships develop is delightful, mostly conveyed in very few lines. It's very clever acting and extremely well played. I loved the growing man-crush, too, especially that nose-nose moment. Beautiful and confident work from the writers and cast.
Speaking of relationships, however, I did not get much chemistry between ML and FL. In earlier episodes she was still too close to her husband's death for that to be appropriate, but even though you could see moments when it should have been developing, later on, ... nah. There was much more chemistry between ML and the kids - beautifully written and played by all three of those actors.
Personally, I suspect that the FL in this case was perhaps the victim of some sort of reconstituted virginity myth in Korean culture. Mums are never seen as fully functioning women, they seem only to exist only as carers and feeders for their families - it seemed that this was in play here, and the drama is much weaker for it, as indeed is the personality of the FL.
Overall, there were niggles throughout this drama, but it was still enjoyable enough to keep my attention.
The plot - well, it's full of holes, and a lot of nonsense, none of the numbers in my head made sense (how is ANY of this secret "government work! funded or reported on? what is Terrius actually LIVING ON in that apartment in the incredibly unaffordable Seoul? Does anybody actually do ANY work?) but that's OK. Let that nonsense go, and you should have a pleasant enough time looking at pretty men doing "thinky" acting or fighting each other, or have a blast laughing at the angst and struggles of some of the other characters going through the circus of life and keeping up the appearances they feel they need - until they don't.
That reminds me, there are moments of light comedy, some of which are actually funny, and they leave quite a warmandfuzzy feeling. Early examples, like when we are supposed to find the FL ridiculous (I think) are not funny for me, but the other residents do offer many mild moments of fun, as well as some quite moving instances of real understanding. They remind me a bit of Shakespeare's "chorus", minor, often stupid or ridiculous characters who actually can hold the key to what is important.
The music - never important for me ... the best film music is such that you should not really notice it, unless it is evoking some internal processing on the part of a character. Here, it wasn't bad, but I did find it intrusive at times, which is not a good thing. In the end, apart from the worst of it, it was mostly pretty meh for me.
Well worth watching this series, but you may need more patience than you expect in the early episodes. I hope you enjoy it.