Perfect, adult viewers drama!
There is no first love and young romance, childhood friends, even no simple motive of revenge.
This is a political drama with strong characters who carry the entire show.

Motivations of people's acting, a desire of the power, dreams of perfect society and state are portrayed excellent.
The main question of this story is that: does the end justify the means? Is this a true what Machiavelli said that everyone is evil and you must do anything to gain a political power?
Surprisingly, although there are some corruption motives, this drama isn’t about corruption, but rather about what politics do and what it looks like.

Director’s job is splendid! The director (Kwak Jeong Hwan) is also an author of Miss Hammurabi, and if you like Miss Hammurabi, you will like Chief of staff too.

The acting is brilliant, because:
Kim Dong Jun acting is better and better.
Elliya Lee, after her odd and makjang appearance in The Last Empress, has a real character to play here and I like her.
Lee Jung Jae and Shin Min Ah (the leads) are amazing. They present serious relationship involved in job and moral dilemmas.
Kim Gab Soo (the true lead!) is AWESOME. Try this drama to watch his impressive performance! I hope he will receive an award.

We all know that dividing drama into two parts has no sense, but in this case it breaks in a perfect time.