My 4 categories are Acting/Cast, Writing, Direction/SFX/Music, Entertainment Value.

Its unpredictability due to its unconventionality saved this drama. As I watched this drama, I negatively assumed a lot about how the plot would unfold, which caused me to lose interest at times. Thankfully, I was wrong.

Acting/Cast: I decided to watch this because I know the two male leads are good actors. They did well, as expected. There were some side characters that also did well. In particular, the casting for the umbrella murderer was perfect - very crazy and scary facial expressions. My main issue in this category is the female lead. The only drama I had seen her in before was Bridal Mask, wherein she also played a damsel in distress. Simply put, her acting skills were just not up to par with the males leads'. She would often go into these monologues where it seemed as though she would change her voice, as if she were trying to lull me to sleep. It annoyed me every time; It was grating on my ears. This could be more of a directing issue though. Her two uncles were over-the-top with their acting. They literally acted like cartoon characters. Actually, most of the characters felt more like manga characters than actual, realistic people. That comic book type vibe is a legitimate directing style, but it's not for me. I prefer watching more realistic characters on screen. 4/10

Writing: For me, the plot saved this drama. It didn't go where I expected it to. It ended up being very different to what I've seen before in Korean dramas. I like how the redemption arcs played out. However, the terrible female lead really dragged it down. I can't even say that it would have been better with a different female lead because the character itself was so poorly written. She was simply a damsel in distress. She was constantly confused, constantly fainting, giving random unsolicited opinions, and doing stupid things. Just because a girl has a weak heart, doesn't mean she needs to have a weak personality, too. She was an extremely one dimensional character. Even after finishing the drama, I still don't know who she is and why these guys are so in love with her. She may just be a Mary Sue. On a positive note, however, the other characters were well done (aside from some minor side characters) and I liked the ending. It showed that all the seemingly random things the female lead would say was actually meaningful to the story, even though the way she would say it made me cringe. 8/10

Direction/SFX/Music: The music annoyed me. I take notes when I watch dramas and I wrote "this music needs to CHILL". It was loud, repetitive, and sometimes didn't really fit the scene. This makes me think the issues I had with the lead female's voice was a directing issue as well. It was as if she had too much gain? The mic was too close to her? I'm not sure. Like I've stated previously, the characters also had more of a manga style to them, which I'm personally not a fan of. Also, I got secondhand embarrassment watching prosecutor Kim Soo Hyuk miming in public for such a long period of time (pretending to be hit, shot, stabbed to death). I was thinking "is anyone seeing this?" I get it, it's part of the story, but why did it have to go on for so long? Flashbacks are part of the story, too, but it wastes so much time. 1/10

Entertainment Value: The beginning was great. Very fast-paced. A lot happened in just the first 2 episodes. I feel the first half of the drama was better that the 2nd half in this regard. I would lose a bit of interest here and there when I would get too frustrated with the female lead or when I was worried the plot was going in a cliché direction. 5.5/10

Overall, I gave this drama a 4.5/10. For me, a weak female lead can do a lot of damage to a drama.
By the way, does Jang Ki Yong play a main role in anything where he's not the son of a murderer?