First of all, the casting was really good.
The drama had me hooked in the beginning, compelling scenes garnished with beautiful OSTs and this left me wanting more.
Along the line, the drama lost direction.
They dragged out the scenes and passed Ji Kang Woo off as the villain when truly, he was a victim of the Deity's harshness and cruelty.
The fact that Hu Sunbae had to be dissipated was really sad, but the more annoying thing was that despite that sacrifice, Dan and the FL still had to go through a lot.
The drama tried to stray away from cliches like 'You who came from the stars' and 'Legend of the blue sea' which have the same Human/Superhuman love story plots, but ended up being underwhelming and repetitive.
Kudos to Shin Hye Sun for bringing her role to life in this drama. I always thought she gave off 'supporting role' vibes, but I think she did a good job in this drama as a FL.

I don't want to give away much, but the drama started off strong and ended off as a huge disappointment.
I don't think I'll re-watch this one, but if it's your cup of tea, go right ahead.