I really like Noroi and Occult, by the same director, and for the most part I really liked this. Unfortunately, it's #2 in a three part series, each by a different director, and so it ends abruptly and irritatingly.
This was great! The plot made sense and had a satisfying conclusion, the ghost scenes were scary, the deaths were creepy. Plus an interesting glimpse of the K-pop factory life for us Western folks. Highly recommended.