Many viewers tend to dismiss foreign horror solely because they feel more comfortable with native language films. My attempts to persuade friends to watch any non-English horror are normally met with great resistance. Horror is about being uncomfortable. Venturing away from that blanket you can hide behind. Horror rips you from your everyday life and replaces that comfort with insecurity to keep you on edge. Language and cultural obstacles in horror can amplify the discomfort and insecurity in viewers, creating a more genuine atmosphere for fear.
Instead of taking in the films in their original forms, we have grown to develop adaptations and re-creations to make the viewers more comfortable and open to the concepts. I must certainly admit that this can be necessary to transfer a great narrative between cultures. A most prominent example of this can be found within the match between The Grudge and its Japanese counterpart Ju-on. To a western audience, Ju-on can be rather slow and components cannot translate between the vastly different horror cultures.
Just as often however, many great aspects of the originals can be lost in translation. One of the better examples in recent memory is in the comparison of [REC] versus Quarantine. Developed first in Spain, [REC] is the far superior film, regardless of audience. The Spanish film created a more genuine sense of horror by utilizing relatively unknown actors and a more appropriate pace. The genuine feeling of panic was relayed far stronger in [REC] partly due to the language barrier. I could dive head first into the film believing that the events could occur in an unfamiliar place.
Quality horror can come from any language and culture, don't let subtitles prevent you from experiencing it.