This movie had several interesting elements: Asian horror style ghosts, twin sisters and flashes of their brutal childhood, and the primary story of a girl searching for her missing twin. At the same time it deals with guilt, fear and revenge. this film just never managed to pull everything together.
While it isn't a terrible film, it felt like it wasted so much of its originality and concept due to the lack of execution. There's a lot of influences from Asian horror movies in this film but not blatant or distracting.
That's the first half of the movie. The second half of the movie takes an turn away from the supernatural origins to a ridiculous revenge plot. While I understand the director intentionally left some parts of the story unresolved, it arrived at such unexpected conclusion via a nonsensical path.
Overall it isn't a bad film. It had a lot of interesting spots, but it took too long to fully develop, and when it finally got going, the story turns and becomes rather pointless.