let me first get the one negative thing I have to say out of the way and i.e. that at times the show feels stretched and I also feel the entire story could have been told in a much more effective and impressive way had they cut down on a few absolutely unnecessary filler scenes (which only slowed down the momentum the story was building) and condensed the story to around 12 episodes..but having said that
this was a very well written and directed show with great performances ...Yoo Ah In as Han Se Ju/Seo Hwi Young was the highlight of the show...I absolutely loved the past story and the friendship of the three freedom fighters..the bromance was funny and endearing and the love story was enjoyable ....the ost added an emotional depth to an already heartwarming tale .also I will give the show credit for having one of the best, most satisfying ending arc for a kdrama... the last 2 episodes were hands down one of the best things I have seen on screen...
My recommendation : have a little patience in the beginning because the payoff for that patience is deeply satisfying !!