The Execution was just Brilliant!!! I get it when some people say it overhyped.. maybe because there are some drama's which needs more attention and maybe the story line of other drama's might be better. But because of that you shouldn't mark it as a plain drama. I normally enjoy drama's where FL has power and where FL likes ML first. This drama is more than that.. you can clearly see character development. How miscommunication can make situations more miserable. Screenplay writing was great. There are some same old scenes like saving FL life in childhood. That was a bit meh..
And one more thing I don't really remember OST of drama's and I don't quite like OST when it goes on repeating.. But I loved this OST and it's very new to me to like OST. I really enjoyed the music. It's quite nice..
Overall my conclusion is go for it!! I loved it it!! It's was a bit smooth ride and not at the same time. If you really want to enjoy 16 episodes without a worry about reality.. GO FOR IT!!!!