It is an awesome production. I rarely rewatch a drama, but this one just cant leave me alone after one time watch. I kept watching and watching... No end. This story line is unique and I have enjoyed every bit of it. The eposide 1, I have found relatively weak start but it just gets its speed up at the end and kept me enchanted to finish the whole series at once. Awesome character development as story progress. I am not very fan about the acting skill of actors. Cant really judge if other actors would have suited this drama better or worse. But at the end, these main actors just seem to be perfect for the whole plot. All credit goes to storyline, if I be honest.