Simply excellent movie in most every way.
Takes a while to get going, and the very opening scenes are very out of place with the rest, and not necessary even. Because the rest is such a trope-buster, this sticks out.
I think my favorite example - being vague to not give anything away - is when the bad guys stage a diversionary attack about halfway through and all the soldiers leave where our main characters are guarding the MacGuffin. Because not /every/ guard or soldier leaves, and the remaining ones are brave, skilled, and professional. The improbably-supervillain leader of the bad guy assault doesn't just walk through, and many, many of his people are killed, on the way to the main-character confrontation. Unlike every horror movie and almost all action movies, you believe it. The good guys don't die because they are NPCs but because they were fooled, they fell to overwhelming odds, etc. The plausible odds make it that much more engaging.
And at the structural level, it's just perfect also. A major character is a senior bureaucrat, so there's a natural link back to the war cabinet, and to the spies of other nations, to allow us to see the whole situation, from top to bottom, with minimal jumping around; we follow the main characters through much of the action quite seamlessly.
Downsides were mostly in that it was a purely Korean production. There was enough US involvement in the plot that a slight joint production would have helped make the American actors seem less trite in characterization, and given them more plausible dialogue. Lots of "simulations" for some reason.
The Netflix version has mediocre captions. Korean seems right, but the English is not captioned and is often very hard to understand. Some signs are titled but not others, or not on-screen information that's important to the plot. Hopefully that will get better eventually also.
