Story: An interesting premise that started strong, lacked in the middle, and ended strong.
(+) the romance is endearing and mature. I know a lot of people had second lead syndrome but I personally enjoyed Manwol and Chan Sung romance. They bicker and tease but there is so much affection and understanding.
(+) finding out Manwol's backstory was interesting
(+) The second couple was cute
(+/-)beautiful CGI- it was really good in the beginning but wasn't as prominent/good later in the show
(-)Because the episodes are over an hour long I easily got bored of the week to week ghost stories. I think it would've worked better if the show was 20-30 minutes.
(+/-)bittersweet ending

Acting/Cast: IU owns this role! Not only is she amazing as the 1300 year old CEO but her scenes in the past- specifically her crying scenes got me.
Jin Goo was also great but his character was not as strong or developed compared to Manwol. He was interesting in the beginning but as the show went on his character was more of a support system to Manwol.
The rest of the cast was great but I'm disappointed that all their side stories were rushed at the end. I would have rather learned about their past than random ghost stories.

Music: Hands down one of the best OST of any drama! It features well known artists such as Gummy, Punch, Chungha, Taeyeon, Ben and even our wonderful IU.

Overall: This drama holds a special place in my heart. Though I can acknowledge the flaws I still looked forward to it every week. My advise would be to not binge it as it might get boring because the episodes are long.