As some reviewers wrote it, this is mainly a soap opera.
I watched the first season mostly for the main actor, Lee Byung-Hun. I really like him (I'm a big fan of A Bittersweet Life). Kim So-yeon and Yeong-cheol Kim are very good too. Seung-woo Kim's acting is a bit limited here but he has a real on-screen presence. The other actors, including Kim Tae-hee, are overplaying.
The story is way too cheesy, the camera shaking during many action scenes is almost unbearable, the plot holes are too numerous to be counted, the spy agencies depicted here are beyond incompetent, etc. I guess there's a cultural gap here since it was a huge success in Korea.
The story is way too cheesy, the camera shaking during many action scenes is almost unbearable, the plot holes are too numerous to be counted, the spy agencies depicted here are beyond incompetent, etc. I guess there's a cultural gap here since it was a huge success in Korea.