dm55’s review published on Letterboxd:
I Saw the Devil is a revenge film with great visual flair, where the camera tells this story so well and so viscerally that I found my eyes glued to the screen one minute and shielding my eyes and recoiling in horror the next. There's very little plot here, but the visual strength and the commanding lead performances propel the movie forward from scene to scene.
I want to mention the score as well, because when paired with the images captured by the camera it brings certain scenes to higher levels of greatness.
I do think the movie is too long, and a perhaps little indulgent in the depravity of the main character (this movie seriously made me uncomfortable more than a handful of times), but it's a very worthwhile experience by the end.