BOne of the best Korean horror? ... Are you kidding? Let's disassemble this train.
Acting was so poor and naive, like one in a B-class 60-s, say, Chinese communist comedy about countryside life.
Camera panning was weird and again naive... Looked like the only editor they could afford had taken a lifetime vacation so they just cut the film with kitchen scissors without any idea of transitions.
Sound is fine... if only one can live with a full-silent background in cabin of a high-speed train on the move.
Naivety of the script was shining bright in the climax full of pathetic (around 15-minutes) dialogs sort of "Oh, daughter, forgive me" "Oh, father, we will stay together forever". Oh, man, it was so damn romantic.
The other thing I liked about this train except decorations and the only somehow impressive scene with a girl out of the pool of blood were weak exploitations of claustrophobic fears with shots in dark tunnel, classic trick with lights turning off one by one and so on.
I would rate this as a B-class Asian horror, nothing in common with higher-class Ju-on, Ringu and more representative genre specimens from Korea like A Tale of Two Sisters or Doll Master.