I was thinking of getting Ju-On and The Grudge 2/$25 at BB this week.... but then I realized that The Grudge wasn't that great and it was supposed to improve on Ju-On.
it was worth the rental. it was one of the better horror movies ive seen in awhile. i really liked how disjointed the presentation was. the story jumped around so much that even if you didnt care for the movie, you were curious to see how it all came about.
The special effects aren't as good as in The Ring, but Grudge's monster/spirt/whatever does get a lot more screen time here than Ring ever had. I think the creepy special effects are interesting enough to justify a rental. Sarah Michelle Gellar doesn't look so hot in this though.