It's actually a really good show with a really good plot plus it's a gogo for kim bum fans he played his role really cool also the leads are my favorite too so it's a win win for those who love kim bum, dong wook and jo bo ah also not to mention lee taeri who's the villian in it he always play soft roles but here he's playing a negative role still cool . I noticed as I watched it till 12th ep I founded out it's a lil similar to korean odyssey like the male lead is in a dilemma to loose the female lead as to save/protect the world from evil like there are many things similar :
1)the female lead waits for the male lead from childhood
2) while in both male leads are dramatically 1000yrs older than female leads plus they belong to a certain animal like lee yon is a fox here whereas sun oh gong was a monkey in Korean odyssey,
3)also teleporting into imaginary or a trap like world through doors , paintings and in both dramas the villian is able to read minds and manipulate the thoughts and could also eat them up to increase their energy lol also,
4)in both the dramas destiny and fate are depicted as cruel twist in their lovestory so there are many more things it would take too long to mention each n every similarity anyways the drama's good to watch!