I'm not sure I understand where all these enthusiastically anti-grudge people are talking about here, perhaps it's just that some people like to rant about things.
The movie was certainly imperfect (uneven acting, some may have had difficulties with the time-changes, actors all too willing to go places I'd really rather not go, etc.) but IMHO there were some things that more than made up for the imperfections.
First and foremost, I LOVED the 'breaking of the rules' bit. NORMALLY when you leave the haunted house the baddies leave you alone, giving you time to regroup, get friends, and find the token mysterious paranormal type. NORMALLY (semi-spoiler alert) when you're hiding under the covers they can only get you through that little opening you peek through. NORMALLY at the end the ghosts somehow have become less creepy because you've found out they're just misunderstood, or they've been freed, or whatever.
Secondly, the production was exceptional. While the movie was hardly special-effects-laden the supernatural bits while brief were extremely well done.
Probably not the best sort of movie for those who think Freddy and Jason are the ultimate sort of horror (nothing against 'em, they've got their place), but great for those who've begun to take the conventions for granted and who don't have trouble with the time distortions.