I do love sageuks. I hardly watch anything else. But I have this problem, see: there is a lot of classism. Their stories are always about princes and princesses and yangbans, and even if the main character is of a lower status they are almost always sure to be a child of a noble family that has been wrongly accused of treason etc etc etc. The actual low-status characters are often caricatures and comic relief. I find this problematic.

So dramas like Im Kkong Jung are a huge breath of fresh air to me.
This is as far from the silk-clothed, baby-faced, elegant jeune premiers as you can get. It's dusty, muddy, raw. There's straw and rags and unkempt hair and unwashed faces and people being horrible to each other. In fact, I don't think there's a worse drama to be a woman in, than this one (*).
The music is heavily based on Korean folk music, with folk singer Jang Sah Ik among others. It is very appropriate and enhances the watching experience.
... which is hard. I won't lie, this is at times a tough watch. Not only the material world is depicted with all its flaws and blemishes, but the humans in it as well. The heroes of this epic are horrible people. One of them literally murders babies. We certainly don't get a glamourized version of poverty. On the contrary, we get a naturalistic depiction of it.
A special mention to the direction. I adored the camera work. The angles, the movements, it was beautifully filmed.

I think I'll watch parts of it again. I can't watch all of it, mainly because of *see asterisk above. So much assault, rape, abuse, oh and that's just from the "good guys".

In short: if you want love stories with princes, this is not the one. If you want a good historical drama that is all about the Korean people who populated the history outside the palace and the fancy villas of the aristocracy, give this a go.