From the minute one I was glued to the chair. The film fulfills its purpose which is to keep you glued to the screen. Is it a scary movie? Of course not. It has a few scares that will make you jump and a few blood scenes (which are very well done). The movie has an interesting plot but it gets a little confusing, and of course it's one of those movies that if you watch it a second time you'll realize you didn't see it the first time, things that will help you understand the plot a little more.
I really liked Seo Je Yi's performance and the cinematography helped a lot to get you more into the film, using very appropriate colors for each scene.
In short, if you like horror movies and want to see something because you get bored, I recommend it to spend some time.