At first, I have low expectations for this. Business or office drama is not my favorite genre. It can be a boring subject. But this drama seems to understand that and deliver the content in a fresh way. Below are the reasons why you should watch this:
1. The chemistry between both lead: Park Hae Jin and Kim Eung Soo is so good, they should get Best Couple Award
2. Every case or problem is solved quickly in an episode or two. I like that
3. Every character is not just a side character, they have their own story. Even the grandma that act as the receptionist
4. The plot twist here and there that make you wanted to watch from ep. 1
5. Even serious event can be a comedic one
6. Lessons on friendships and office teamwork are told smoothly with fresh scenarios
7. Marketing strategies that some of us can relate to.
8. A funny ending and anti-cliche one (I like the ending)
9. The trot songs are refreshing compared to pop songs in all dramas

Hope the writer create more script like this. Kdrama seems to run out of ideas.