- no plot holes; even minor plot arcs are formally tied up, and you don't feel like they're forgetting anything at all. this is probably thanks to the extended 20 episode length -- they got everything that they wanted to in

- satisfying ending for all characters, again even for the minor supporting characters. everyone got their fair share of justice, and likewise their ending is satisfying and you build an emotional bond even to characters that were so minor due to the memorable writing that were perfectly played out by their actors

- brilliant acting; the ability of the main actors to turn from mischievous, to playful, to remorseful, to every single emotion in the book is second to none. i was super surprised to see that ok taecyeon play the main antagonist role (especially after watching him in save me, another great drama) -- but he exceeded my expectations and managed to make me despise his character and everything he did, even with that beautiful face!

- brilliant screenwriting -- the writers KNOW this plot is absurd, so they go full in and embrace it. this is the right way to approach these sorts of dramas; even when something happens that seems completely ridiculous, they've built the foundation of the characters so well that you think it's completely plausible they might do something despicable and or so stupid. you feel like you're apart of the family of protagonists, which is such a rare trait for dramas to have and is another testament to the screenwriter(s)' flawless storytelling.

- great use of special effects; EXPLOSIONS GO BOOM!!!

- memorable soundtrack (shoutout john park)

- memorable moments and gags (shoutout inzaghi and his pals)

literally a flawless kdrama