Exorcism isn't a good movie. But it's not so much a terrible movie as it is just a dull one. While Exorcism doesn't copy The Exorcist (1973) scene-for-scene, it has enough similarities that you can't help but compare the two and come to the conclusion that this movie doesn't come close in any aspect.
Have you ever seen this?
(http://fight-evil.com/movies/e/exorcism-1975/2.jpg)