I understand that it's not what most viewers expected, even I was a little disappointed. But the thing is romance isn't the #1 priority of this drama and the drama itself is darker than SWDBS.
Nam Soon is an agent and it's important for her to keep her enemies closer. Hee Sik may not be portrayed well as you expected but he always got Nam Soon's back and is always there for her. Nam Soon and Hee Sik needs one another.
Shi Oh has a tragic background (which I do feel bad for), but that does not excuse his criminalistic behavior and attitude. The law will arrest all kind of criminals. Shi Oh is handsome and sexy but to me, the purpose of good-looking villains are to convey the: "Angel face but devil personality".
The season is going to pick up the pace again somehow in the next episodes, we still got more to wait, so be patient, I'll send another review once the series' status is completed
So many things I wanna say but I can't express it.
Feel free to fight me as long as it's a debate and not an argument.