I've seen The Grudge, and all I can say is that if you are planning to see it, then get ready to be really, really scared. It's probably the scariest film since The Blair Witch Project was released. It's one of those horror films when you know that something scary is about to happen, but you just don't know what or the EXACT moment when it does happen. Also, it doesn't show gore in an attempt to be scary like most horror films nowadays. Instead, it's psychological, which proves to work much better.
When I saw it, I jumped on many occasions, and one of my uni frienRAB who I saw the film with was very scared. She had to cover her face with her hanRAB during the frightening parts.
It is a VERY scary film, and one well worth seeing.