This was a really great watch. Great plot, pacing, and characters. There is a lot of depth to each main character. You can see the way they were shaped by their experiences and their choices. All the actors were amazing as well, making the story come alive. And all this is backed by one of the best cinematography I have ever seen. Just those picturesque scenes gave me more than enough reason to watch the series.
[I especially loved the settings which were colour-coordinated. Having all elements in a scene match a particular palette was incredibly satisfying.]
I realise there is a lot of dispute about the history in the series, and the depiction of certain characters. I agree there might have been some elements that were inconsistent with historical facts. I personally did not, however, feel any political narrative. More than a commentary on the nations and their actions, I found this to be a story of the people caught in this tumultuous time. To me, the series felt like a narrative of their lives, their choices, their experiences. It felt beautiful and real, and heart-breakingly sad at the same time. A definite must-watch for all drama lovers.
*SPOILER ALERT*
Do not go into it expecting a happy ending. I held it together for a while, but lost it when someone brought in Gu Dongmae's katana to the pawn shop. "Do you take this? I found this on the street." Completely broke me. The conclusion still left me feeling more hopeful than depressed, so points for that.