Mixed feelings about this drama.

The good:
1) IU's acting is so good! I'm a huge fan. The heart of this show is, without a doubt, IU. She stole every scene she was in. I also loved her outfits. I really felt for her - her past and current self.

2) Main plot was really solid. The flashbacks to the past, Jang Man-wol's past, all of that was really compelling. I loved her story with Go Chung-myung, and her familial relationship with Yeon-woo.

3) This show is absolutely beautiful. The set designs, the cinematography, the outfits... absolutely beautiful.

4) I love Sanchez.

The bad:
1) Too much filler episodes. Each episode basically comprises of about 70% 'ghost of the week' and 30% Man-wol's past/flashback to the past. Some of the ghost side characters had really poignant stories. The rest, I really didn't care much about. I only see them for about an hour, then they're gone forever. Also, Man-wol's past is fascinating and compelling, and it ended up being frustrating that I couldn't find out more about it until the end.

2) I did NOT buy Gu Chan-sung's romance with Man-wol. I was way more invested in her and Chung-myung. I felt for him and his failed and tragic romance with her. They really seemed like doomed star-crossed lovers. The minute Chung-myung appeared, I kind of switched ships. I saw Chan-sung as Man-wol's brother and started skipping their romantic scenes because I just wasn't filling in. Chung-myung made a way more compelling love interest. Sadly, the writers obviously did not think so.

3) Side characters that were never developed or fleshed out. Unfortunately, I didn't care about most of the sideplots or side characters. They barely got any screen time.

4) Gu Chan-sung has no personality outside of being in love with Man-wol. He ends up functioning as an impetus for plot stuff to happen, with no real presence of his own. His character was quite poorly written - he did not feel like a main character.