The Conjuring isn't the scariest film of all time and certainly not a cinematic phenomenon that you shouldn't dare miss. Period.
But the monstrous box office success ($200 million and counting), the overtly positive reviews and the high pitched marketing campaign, even in India, suggests otherwise. Indeed, the movie has got a few spine chilling sequences that can truly scare the hell out of you (In fact, during one of those scenes, a girl sitting next to my friend squeezed his wrist so tightly that the poor guy almost screamed writhing in pain.) Yet The Conjuring breaks no new grounds. It isn't as scary as The Exorcist or The Evil Dead (a movie which can give me sleepless nights even today). It doesn't explores a new genre in horror like Paranormal Activity franchise. The film doesn't even has that suspense angle to all the supernatural activity that catapulted The Ring and The Grudge to a great success.
In spite having none of the above, The Conjuring works; and works pretty effectively.