It is a movie with an intriguing concept and it tries to tell a possession story seen through the Native American culture and not through the eyes of the Catholic Church. It manage to build up an atmosphere too until a bizarre "birth sequence" scene with a medicine man coming to life. What doesn't satisfy is the absurd spiritual and magicial battle between demon and technology ending.
Really just awful. There's definitely some fun to be had here (with a very drunk theater full of schlock cinema fans) but it's not entertaining enough moment-to-moment. The MST3K treatment would do wonders for its watchability!