This was originally advertised as the Japanese original (Ju-On) but by the time it was shown at the Student Cinema, it had changed to the American remake.
Although I have yet to see the original, this seems to be closer in spirit to it's Japanese origins than the disappointing remake of Ringu (most likely due to The Grudge retaining the same director as the original). It was one of the most effective horror films I've seen for a number of years - special effects were minimal but the make-up on the 'spirits' was excellent.
Overall, well worth seeing.