I absutely loved this. I wasn't really sure what to expect after reading the author's note about kdramas etc as I've never watched any. But I had such a great time with it! 
The Korean folklore/mythology was so very cool, I did have to google a fair bit but I didn't mind that at all. All the creatures were so fascinating. 
I absolutely adored Hani and Seokga. Their dynamic together was everything, the banter was top notch. I loved watching their characters both grow and they both had amazing character growth in just one book. There was such a good mix of funny lighthearted moments mixed with more deep emotional moments. I loved the romance subplot. 
I wasn't sure if I would enjoy the mystery/detective/cop element but it was really fun and entertaining. Some of the twists were predictable but I was surprised by others! 
The ending!!!!! Gosh the ending. I did shed a tear. Cannot wait for book 2.