Very good drama overall despite its flaws.

What I liked :
- Awesome cast
- Great acting overall
- Great pace overall
- OST that had me dancing or playing drums on my table.

What I disliked :
- Some characters were lacking in depth or missing something.
- The ending leaves (too) many things unresolved. The last episode looks like it is missing some scenes !
- The love between the "original lead couple" was too shallow, contrasting with the story. And there was no resolution.