Tale of the nine tailed is about the adventures of the nine tailed fox lee yeon and his half brother lee rang.
AND...that's it. So if you like the characters and then you would like the drama. if you don't then you won't. simple.
There is no overarching storyline or plot. Their relationship is what makes this drama special. Lee rangs relationship development with his brother and close to father AND mother figure, lee yeon who loves and cares for his brother with exasperated fondness gives this drama life.
The writers banked on developing that relationship in season 2, cut off on the annoying romance angle for lee yeon, added some new chars, upped the intensity and horror and that's season 2 in a nutshell. There are some glaring inconsistencies and plot holes thats hard to ignore thanks to the rushed execution.

What I loved:
- THE BROTHERS RELATIONSHIP DEVELOPMENT
- THE HUMOR
- THE PRODUCTION VALUE
- MORE FOCUS ON DEMONS, FOLK GODS AND THE LORE

What I didn't like:
- the char sunwoo eunoh was badly written and badly acted.
- hyping satori up only for him to be KO'ed after 5 mins.
- Lee rangs insta romance w the mermaid
- VERY rushed execution
- Lee rangs sudden power up which was...convenient but not logical.

It's a great drama for entertainment value and I love watching lee dong wook being sexy and charismatic and the humor moments are pure gold. Plus Kim bum's lee rang is one of the best chars I've seen.

There would likely not be a s3 but I hope there is.