Disappointed with the movie I watch

Two days ago, we watched the movie entitled "The Last Exorcism" at the cinema. Hubby and I did not check it through the net what kind of movie it was, we only watch the poster. It looks scary in the poster and so we think the movie was scary too. However, when we watched it, we were disappointed because it's something that we did not expect. We thought it's a movie with many actions, but it some sort of documentary. Not much action, but it's more on talking.