The idea and concept for this drama is actually really good and mature. however its execution is unsatisfactory.
The actual drama and action (basically the interesting parts) were crammed in the last 2 episodes while every other episode in the beginning is just boring and a waste of time. Maybe if the storyline was balanced out abit more it would be more interesting. i think its worth a watch if you have 2 hours to spare but theres no rush to watch this.
the acting was good, i think the writers could do a better job in keeping the personalities of the characters more consistent but other than that i dont think the cast and characters are a problem.
(also theres alot of unnecessary "flashack" scenes, the time could have been utilized better. i noticed there are weird skips and transitions from one scene to another due to lack of time but it could have been fixed by lessening the flashbacks.)