This had a solid story, good cast and acting, cool music, and in general a quality production. The only thing I can put my finger on was that it was too dark at times, especially when watching on a small screen (mobile).

The story was well balanced; there was build-ups (suspense), intense fight scenes and action, and personal stories for some of the characters, seasoned with some light romance on top.
The story was a bit predictable, but not sure it would have been better if it hadn't been.

The whole vibe is a bit like a good old fashioned western, but it fits quite well.

It can't quite measure up to my two favourite historical Kdramas Mr Sunshine and My Dearest, but then again I feel it necessarily shouldn't be compared to those either. But both of those are amongst my highly recommended series that I also probably will rewatch one day.
Not sure I will watch this again, though.