Just a note, I'm not one to watch historical dramas. But this was definitely one of the best (and even have the urge to rewatch) despite the ending.

Storyline, acting, cinematography, OST, idioms used - everything was done SO WELL.
Both the main leads have solid acting and they have brought out the characters even with the small things, such as their hand gestures, eye contact etc. Even so, all other characters acting were so good, to the extent I actually hoped there were more episodes just to include the other side characters stories! The music - it fits so much with the scenes and its just astounding!

I'm sure everyone already knows the ending for this drama to be real sad. Let's say I don't favour dramas with extreme sad drama-line for the leads cause it just feels depressed. But the story for OAO was so well executed to the extent I am so into rewatching, crying my eyes out, and subsequently watching FAE to heal my sadden soul for their past life.

This is definitely a nice drama to watch. For those who were like me that are not into historical ones, just try it! There would be FAE for you to watch after this anyway haha. Ps. just remember to prepare some tissues mostly on second half of the drama :)