Every single element and almost every scene in this movie is derived from another horror film. You can read the whole thing as a tribute to other movies in a Tarantino-esque manner (unsurprisingly, this is one of his own top ten films of the year so far), and I'm sure that's meant to be the case, and yet I cannot deny that Wan fashions the frights and shocks effectively and paced throughout the film, never letting up for one minute and giving audiences, especially horror buffs, exactly what it is that they came for. It's really not a film for the weak of heart. Even his filmmaking style is a tribute to 70's B-movies, with an opening credit sequence styled directly out of a 70's film and the silly dialogue and kind of ludicrous plot left on the surface level only, right down to the direct endorsement of the catholic religion as the only protector against all evil. The performances are all good, especially Lili Taylor as the mother of the family, who becomes possessed by a demonic spirit, but the exorcism scene in particular bordered on camp after just a few minutes, and the first half hour or so was filled with way too many of those horror movie "false starts," where you think something's going to happen and doesn't (I hate it when that's overdone in these movies, and for me it was here).
So, all in all, mixed feelings from me on this one. It does what it's supposed to and yet with so many direct lifts from other movies I feel it's at fault for not bringing at least something new to the table. Are we at the point now where there's nothing original left to do in a horror movie, has it all been seen and done at this point? The Conjuring wants to be a 70's B-movie at heart and for that purpose it reaches, but not exceeds, its goal.
* * 1/2