I know I'm in the minority, but I've always considered The Exorcist to be a rather dull film when the pea soup isn't hitting the fan. Exorcismo, a Spanish Exorcist rip-off starring Paul Naschy, is boring even when the possessed girl is doing her thing, and only regular nudity from its pretty female cast members prevent the film from being a total waste of time.
The girl with the demon problem is Leila (Grace Mills), whose heretical activities with a local Satanic cult has left her possessed by the malevolent spirit of her late father. Naschy plays priest Father Adrian Dunning, who is called by the girl's stepmother to lend his expertise. Meanwhile, people are turning up dead with their heads facing the wrong way.
The main problem with this film is that Leila doesn't develop cracked lips, crazy contacts, and bad complexion until well over an hour into the film, and even when she does, it's not very impressive, the few pesetas in the coffer not nearly enough to replicate the head-turning, vomit-spewing craziness of The Exorcist. With everything leading up to the possession being boring (nudity excepted), and everything after being almost as boring, the result is... well... boring.
Bums, boobs and bush aside, the only thing I found remotely interesting was that, despite being Spanish, the film was set in England (although certain shots of arid countryside are clearly not the rolling hills surrounding Bristol), and that Father Dunning is only too happy to carry out the exorcism without the go-ahead from his superiors (I always thought that express permission had to be granted by a bishop).