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

If I were to rate the 1st half of this drama and the 2nd half separately, the ratings would be very different. Let's just go through the categories and I'll explain:

Acting/Cast: Easily the best thing about this drama. In the beginning, I was iffy about some of the characters. However, well before the end of the drama, I liked every character and enjoyed all of their roles. 1st half - 6/10 ; 2nd half - 10/10

Writing: This category can be broken into 2 parts - character writing/dialogue and story writing. Throughout the drama, the character writing was well done. Everyone had very distinct personalities that felt real. I easily became attached to multiple characters. That being said, I felt the male lead was the weakest in this department, especially in the 2nd half. His character felt like he had the least development. I knew the other characters so well, but the male lead remained fairly mysterious. Although, I also realize this was intentional, but I still didn't like it. Now for story writing...great in the 1st half. I loved the light and fun vibe of the 1st half. It was very charming. My only gripe was the writer's overuse of red herrings to the point of slight annoyance. I also thought the cliché stalker plot point didn't fit in well with the feel of the drama. It was also quickly glazed over like it never even happened, which made it feel even more out-of-place. In the 2nd half, the overuse of red herrings became obnoxiously ridiculous and those cliché out-of-place plot points were, unfortunately, here to stay. How can I put this simply? The story became confusing, unrealistic, and I haven't been so pissed of about an ending since Black. The ending ruined the entire drama for me, just like what happened with Black (which, oddly enough, stars the same female lead). It's as though the writers didn't know how to end the drama and they were fighting with each other and changing their minds every episode. But, what makes it worse, the writers were foreshadowing the ending from much earlier in the drama. It makes me believe that this mess was completely intentional and I'm shocked. And what's even worse, I feel betrayed, emotionally manipulated, violated even -- similar to how the characters in the drama SHOULD have felt about the whole situation. 1st half - 9/10 ; 2nd half - 1/10

Direction/SFX/Music: Almost no complaints here. However, I am reminded of that one scene...the piano on the beach. I was so confused. Very out-of-place scene. Was it a dream, was it a fantasy? I hope so. Regarding the music/OST part, the OST is nothing special; not my cup of tea; it neither caught my attention nor annoyed me. However, the piano music was great. 8/10

Entertainment Value: I got through this drama fairly quick because it was fun and had likeable characters. In the 2nd half when crazy random things were happening, I'm not going to lie, I was entertained and the cliff hangers got me through the drama even faster in the 2nd half. I was extremely curious about how the writers were going to play out this ending. I was hoping the male lead's mom would get some kind of redemption arc. I was hoping everything would come together and make sense. It seemed like it was heading that was until suddenly -- the writers forgot how to write and my hopes were shattered. 1st half - 4/10 ; 2nd half - 6/10

Overall, this drama would get an unweighted score of 6.5/10, technically speaking. But since the ending was drama-ruining, my weighted score would be 3.5/10.