I'll start off by saying, that if you're looking for a great epic love story with complicated plot, this isn't it. Even though the whole drama is about 5 hours long, I didn't think they used the time wisely.
If you're looking for a drama where you can turn off your brain and not think about the plot too much, this is the kdrama for you.

The negatives:
The ML has serious issues with communication with other people and is the stereotypical kdrama lead, and, even though I thought that his issues would be resolved, in the 17th episode I lost all my liking of him, when he said, that he would like the FL to cry. I know it was meant to be petty, but it ruined all the work he had done with his personality.
The dragging of the plot. Even though the drama itself was short, I felt as the romance was dragged out way too much, like, they started dating in the last episode, like, what's up with that?
What was up with that clown?! I was hoping that they would explain it, but nothing...

The positives:
I liked the supporting characters, especially the manager of the CEO, he was typical comedic relief, but I enjoyed them
The lack of a mean second female lead. When they introduced the FL to the company, I dreaded the possibility of the blond girl being the bitchy 2FL, I'm glad they exceed my expectations
The title song - at first I thought it was annoying, now I know it's annoying but it doesn't stop me from humming it from time to time