"The Exorcist" is a classic and a must-see for its influence on the whole genre. The athmosphere is great, several scenes are as superb as they are infamous. Linda Blair really is a superb actress, especially if you see how old she was when this movie was released. The make-up also is amazing.
The theme by Mike Oldfields also is very good.
I know that som younger viewers found this movie funny rather than scary. However, this does not mean that this movie is unintentionally funny. It just means that times changed and other things are scary nowadays. Fans of thrills of older classics will enjoy this.
(SPOILERS may follow:)
The movie is about a possessed girl. She spins her head around, gets thrown up and down in her bed, levitates, etc.
Most of the scary scenes are referenced to in several other movies and series, so even kids will be familiar with them.
-In the director's cut the girl twitches back and walks downstairs like a spider, then she spits out blood and makes a strange noise.
-A death (murder?) is a theme, but nothing is shown, not even the corpse. Graphic violence references.
-The girl gets totally scarred.
-An exorcist is found dead.
-A girl uses a crucifix to mutilate her private parts (no nudity, blood on the crucifix and the clothes) and yells: "Let Jesus F*** you" repeatenly.
She then rams her mother's head against it, who gets completely bloody.
-A death near the end is emotional, but not graphic.
-The girl uses strong language, mostly f- and c-words.
-The girl uses rude geistures, urinates in front of people, insults god (for christians), asks people to have sex with her the crudest wayd and vomits.
However, this movie should be rated 15 in the UK and Ireland, not 18.
I think nowaday's the movie is okay for viewers 14 and up, because most of them have seen things way more scary, violent and sexual. And language is present in real life, too.