Well, something of an East-meets- Spaghetti-Western, with really good sound track and great action. Perhaps most of the similarities end there, but they are all pretty great. The specific setting and period means that the similarities are limited to what the time and place demand.
Set during the early 20thC Japanese rule of Joseon much of the action takes place in Gando, a border area claimed by both China and Joseon, with a frontier desert landscape peopled by bandits and "questionable" characters. The landscapes and towns / villages represent almost further characters in this drama, with some stunning cinematography showing its beauty and harshness.
Great costumes and styling, with attention to both Joseon and Chinese traditions all in a state of transition into the modern world. These somewhat show the complexity of these communities on the edge, all rigidly overseen by Japanese army aiming to secure full control of the people. This conflict is particularly significant because Gando is remote, logistics for the Japanes are difficult and the area is in fact a centre for the small liberation movement made up of different factions who are not aware of each other but aim for similar goals.
Japanese occupiers see native Joseon as mere animals, even where they adopt Japanese customs with loyalty to the Emperor. They routinely massacre entire villages or towns and abuse Joseon people in all the usual ways
Lee Yoon is a phenomenal gunman and fighter, and of course KNG has incredible charisma in this role. But while the man with no name was a loner, Lee Yoon is a brilliant military leader as well as moral giant, has his own struggles but is still a truly 'ideal' man, rising from slavery to genuine greatness.
Lee Yoon's former master/owner, Kwang Il, was supposedly kind, and did free his slaves. However, now a member of the Japanese army, he has fully adopted their ideas, mostly as a self serving strategy. When Lee Yoon severs his friendship/ connection to him, he resolves to have him killed, using a female assassin who as a child escaped her village's massacre and now lives only to survive.
In the meantime, Li Kwang's fiancee lives a double life.
The tensions in the area are complex, with bandits in Japanese pay, others just thieves, others fighting to undermine the Japanese, a kind of mainstream independence movement (playing a very minor role here), Japanese regular army plus Japanese colonial forces (who jostle for power), and of course 'middle class' settlers who are probably loyal to the Japanese, and peasant settlers who could be in Japanese pay, or rebel spies, or simply looking for a quiet life. But it's not very obvious who could be who.
The story is lively, with lots of locations and lots of action, including different levels of battles between factions. Of course there's a love interest, but while it's one of those soulmate passion plays, it's very low key and is left open ended.
I really enjoyed this series. It feels gritty and authentic (though the recovery times for multiple injuries is rather ... optimistic). Characters, even where support rather than main, and even where quite minor roles, are well written and well portrayed – with many familiar faces in play. I loved the visuals, and how it is presented with so many echoes of classic westerns, yet never losing its sense of place. The music is great too, and well suited to the action and mood of each moment.
I'm trying to think of flaws. But I can't, unless I nitpick really hard – for example I wasn't much into the romance moments – but the actors and performances were very believable and chemistry was good even if subdued which was dramatically appropriate.
The ending is slightly rushed and inconclusive, but since we have reason to look for S2 I thought it was OK.
Kim Nam Gil has already leaked the question of an S2 stating that if there is another series it won't be made by Netflix. I am intrigued by what happened behind the scenes to prompt that – or whether it is issues on profit shares – wouldn't be the first time.