I came across this movie when I was going through a list of dramas and movies starring Nam Gyu Ri (I liked her in the drama '49 Days'). I realized that this is a horror movie and its synopsis interested me so I thought about watching it as I didn't watch horror stuff for a long time (and I'm a great horror movie/shows buff).
This movie has an interesting plot and it actually creates the anxiety in you that not every horror movies does. The story is pretty unpredictable, making you wonder what is gonna happen next. The ending was totally unexpected (at least I didn't expect that kind of ending). There is definitely blood and gore- feature of a typical horror movie but I don't think to the extent that will make you go 'Ewwww' and quit the movie.
The cast is fairly good. But I don't remember the music. Did anything really play in the background? I don't know. I was probably too busy watching people die one-by-one that my ears didn't pick the background music.
The reason I gave the rewatch value 8 is because this movie is highly thrilling and even though I will know what's going to happen next when I watch it again, it is fun.
To sum everything up, I would say that if you are a horror buff, then this movie is worth giving a try.