Overall it was a very good fantasy romcom, one of the better ones. The chemistry, the comedy, the visuals and the actors were the most outstanding part of this drama. It was a fun watch, BUT the writing was lazy in the final few episodes. There was no good explanation to Gu Won’s return, it was also rushed and I missed the character development on his part. I do not undertstand why the series spent so much time exploring on how he is getting back his human self if in the end he stayed a demon??!! I think it would have been a much better arc if the ending is him making peace with his humanity and comes back as one. Maybe he could have given up on his powers in exchange for a human life with Do Do Hee.
Keeping everything as it was is very lazy writing in my opinion.
I think Destined with you was superior in this sense even with all of its flaws.

Anyway, it is a fun watch (especially the gang), but do not expect anything out of the ordinary.