Good movie, not the typical frightening scenes (although there were some) throughout the movie. The movie had a few side plots, for example the story line in regards to the Spanish Inquisition.
I've read many reviews of people upset saying that the CGI wasn't to par with today's technological advancements, or that the voices of the possessed hasn't changed since the birth of exorcist movies.
This movie only had a budget of $18M, which is peanuts in today's age of filmmaking, therefore, the CGI capability was clearly limited. The studio clearly wasn't expecting a big return from this genre, and rightfully so since the movie only made $76.2M worldwide.
As for the voices, they are a part of the genres historical past and engraved into people's minds who've enjoyed them over the decades. Would you change the voice of Darth Vader in a remake of Star Wars?
That is all.....