I loved it. I loved the Ha-Won and Ji-Woon pairing even though there was a lot of backlash in the worse ratings of this show. I loved their personality mix and honestly felt like they had more chemistry than anyone else. In my opinion, I felt the final pairing was kinda obvious from the get-go from the writing and cinematography. I liked the love triangle with Hyun-Min, though his pairing with Hyie-ji was annoying. I thought she had no motivations or goals or personality besides moping.
I liked the plot-twists and many storylines intertwining (I recommend watching the series all the way through).
My only complaints with the writing was that it felt like they added information last minute with flashbacks. I would have introduced information or characters earlier into the show. I also felt like they wasted screen-time going over things that happened previously and it was overly explained. Let the viewer enjoy and recall things themselves.
And then my complaint with Hyie-ji. It was slightly redeemed, but the fact I hated her for a majority of the show was enough said for her character.