It's probably one of the most enjoyable dramas I've ever watched! It doesn't tire you out nor does it feel draggy. The story is very novel and fresh. The characters are well written: funny whilst maintaining a good amount of depth so as to not seem too superficial or fake. Also the comedic element is abundant in this drama without turning it into a farce. It does have a turning point, where the story gets slightly more serious but that does not take anything away from the plot, it rather enriches it and makes it more balanced.
Moreover, the acting is great, the OSTs are beautiful and the chemistry between the leads is remarkable. All in all, it is a really enjoyable and entertaining drama, I'd definitely re-watch it (as I've already done, a couple of times) I strongly recommend it.