Honestly, I only watched this because Joo Won was in it. However, I really enjoyed it. The story is intriguing even though sometimes I thought that they were inept as spies...but hey, it is just a drama. The pace of the episodes was well done and the character development was good too. I had no idea if Do Ha was good or bad and I guess in the end he was a little bit of both. There is also a story that Woo Hyuk tells to Mi Rae and JJ that I thought was really good. Also the ending was satisfying. Joo Won can do no wrong as far as I am concerned. His acting ability is off the chain. I mean just compare his roll in Bridal Mask to Gil Ro and you can tell that he is versatile. I liked Choi Kang Hee in Protect the Boss and she does another outstanding job in this drama. She plays smart and adorable as Seo Won. So, who knew that Chansung could act? I certainly didn't. He had me bewildered as to his true intent as Do Ha up to the very end. I really like that in an actor. Of course, Uhm Tae Woong's cameo as Woo Hyuk is daebak. I love him. Im Yoon Ho as JJ and Kim Soo Hyun as Mi Rae had me in tears at the end of the drama. I was actually routing for the "bad guys" by that point. I enjoyed the music. Even if you don't watch this drama, then you should definitely add Big Baby Driver's A Stranger to your playlist. I will probably rewatch this at some point. As you can tell, I was totally invested in the characters' stories and I recommend that everyone watch this.