CONTAINS VERY LITTLE IN THE WAY OF SPOILERS, OR INDEED ANYTHING ELSE
If we believe the IMDb, then this is actually number five in the Amityville Horror saga. But that's only if you rank it as an actual Amityville Horror movie with That Spooky House and not just a bog-standard possession/haunting horror flick that just happens to be set in a town called Amityville but has no connection to the rest of the saga.
The Amityville Curse is actually a pretty bland affair, despite the 18 certificate; there's no sex or violence or much in the way of swearing, and only a few effective and well timed jump moments. Five people get together to buy a house (discovered on the premonitions of one of the women in the group) only to find there's a presence doing the usual things: throwing books off the shelves, turning bathwater into blood, smashing crucifixes, and so on. As usual the guys in the group are dumbasses, convinced that's all the mysterious events can be explained away rationally and are not in any way paranormal, and they're absolutely nothing to do with the unexplained death of a priest in the confessional several years ago. The fools.
I've no problem with haunted house movies: most of us live in houses, or have done at some point, so a domestic setting for a haunting is something we can all relate to (unlike, say, a puzzle box that calls sadomasochistic demons from alternate dimensions, or an ancient book of spells that call the dead to life). But it's really got to be done with more energy and verve than it is here: this is a lifeless, dull movie which feels like a TV project and never picks up enough steam. Despite the occasional "boo!" moments, it's not worth the time and effort.