A problem I have with a lot of horror movies is inconsistency of their idea, or explanations that don't really make sense with the rest of the story. Winchester, however, did a great job at remaining consistent with their story.
It relied on a number of jump scares, which were well done. The story was interesting and bizarre and was at least partially based on real people. Not terribly scary, but a good deal of suspenseful horror. 7/10