This is just another K-Drama, and in my experience every K-Drama is fantastic. The storyline was great, presentation great, comical relief great, serious plots great, along with every actor being their best or even perfect self.
However, I would give it 4.5 (though they look 4 out of 5 stars) despite having some unexpected turns because some critical moments, and scenes in between, seemed unnecessarily rushed, just like the end.
Worth-watching nonetheless, and hopelessly romantic might give this K-Drama a 5-star rating.
Fell in love with Kang Han Na in this one...