The Amityville Horror is at heart a story about the perils of real estate, and how families have to sometimes cope with the unexpected. What do you do when your house unexpectedly tells you to kill everyone in your family? Answer--make sure you're the one armed with an axe!
The 1979 film featured Margot Kidder (whose actual life would turn out more horrifying than anything in the film) and James Brolin, who has a great meta-moment when he hollers "Mother of God, I'm coming apart!!!" when he peers into the future and realizes he will someday be Mr. Barbra Streisand. The 2005 version stars Ryan Reynolds and his impossible abs, and both versions are based on the true story--in 1974, teenager Ron "Butch" DeFeo murdered his fambly with a shotgun and a few years later the Lutz fambly moved into the home. The Lutzes claimed the house was haunted, but later it turned out to be a hoax.
What makes little sense is that the family in both films stays in the house way longer than they should once it's clear the place is a portal to hell. This might make sense if they'd just moved there from Detroit, but no such allusion to Detroitism is made in the movies.
Just once though I'd like to see a film accurately portray how people would act in a horror situation. Something like:
1) The victim is wandering in the dark, and shouts out "this isn't funny, guys!" and then the killer shouts back "okay, I can do some Don Knotts impressions if that's more your speed."
2) There's a point where one victim says to the other, "hey, why don't we call for help with your cell phone?" and the other victim says he's really really short on minutes and doesn't want to waste them.
3) The killer pops out with his chainsaw/machete/axe, and the victims turn out to be Texas Republicans and they casually gun him down because they go nowhere without their .357s.
4) A surprise twist, where it turns out . . . they were on Earth all along!
5) They find out the house is on an Indian Burial Ground, and are cool with that, but then the Bureau of Indian Affairs repossesses the home as it belongs to the tribe and the victims have to move into a condo.
6) The pre-teen girl is possessed by a demon, but no one notices because she's been a bit of a pill lately anyway.