Usually, when a director wants to set a dark mood, he or she relies on shadows and gloom in the camera frame. Here the exact opposite has been achieved through the perpetual midnight sun which throws the descent of Jonas Engstrom into madness all too clearly. At first the effect is subtle, but as the picture continues and there is never any nightfall one begins to feel the same bone-deep weariness and lethargy experienced by the protagonist. I watched it for the first time late at night and it completely threw me off my sleep cycle for the night. Most powerful.
I speak neither Swedish nor Norwegian, but I didn't find the subtitles a hindrance at all--indeed, I much prefer subtitles to dubbing every time. I found that I had to work harder to notice everything that was happening on screen, which was a welcome change from the constant "eye candy" that seems to be the norm coming out of the movie business these days. All of the performances were understated yet brilliant, especially, of course, that of Stellan Skarsgard. I was particularly intrigued by the opening title sequence, showing the murder through the eyes of the murderer in a disjointed and confused sped-up manner, and this point of view is a foreshadowing of how both Engstrom and the viewer will feel by the end of the picture.
I have not seen the remake yet, and I'm not sure that I want to do so. The Hollywood movie business never seems to know when to leave well enough alone. I'll be able to make a better recommendation when or if I get around to the remake.