Story: Each episode has its own story and the main story develops gradually, little in each episode. This is the standard kdrama framework and this drama makes use of it really well. We can see the character development of the male lead with each short story really well. They don't feel like fillers. Don't let the "I can see ghosts" overused theme bother you, because if you ignore that, the story is really good. It is certainly not scary. Maybe a little in the first few episodes and one of the later episodes, but overall not scary. It did drag a bit in the end though.
Acting/cast: Pretty good! They just fit in their roles. I like all of the leads in their roles. Love when the main leads smile.
Music: I don't know much about music, but it definitely added to the feel of the drama. I liked it
Rewatch value: I binge watch Kdramas. I watch a couple of new ones and when I still don't feel satisfied, I go back to this gem, smile like an idiot and go to sleep after finishing it.
Overall: Pretty sure you will like it if you're not too scared of ghosts, and don't mind a tiiiiny bit of dragging at the end.