Okay, I'll be the odd one out here. (I like it.)
Spoilers >>>>
They did a good job setting tone. Right away, I like the Alice and Rebecca characters. Immediately, I don't want Alice to be left alone in that house. I do genuinally get creeped out at the house itself. Good job, set designers. Nice acting from Brittany Murphy when she is deathly afraid of someone being in the house for the first time. Good performance by Thora Birch as the uncomfortable, sad housewife Lucy who is becoming slowly worn down and dillusioned with her controlling husband. I also like how the Rebecca character is a bit mysterious. I thought for a few seconds here and there that she could be in on it. (The actor, Tammy Blanchard, confirmed in the "making-of" featurette that she had intentionally played the character that way. I like that I picked up on it, because it was subtlely done.)
I don't know why people always need a blown-up Hollywood mega twist ending. I've seen other peoples' "re-writes" here in the comments section, and to be honest, those are kind of predictable too, albeit fun. The simplistic ending is creepier in a way, because it is something that could happen to anyone. The power of the mind is strong, and we all have a dark side.
Straight-forward story. Simple set design touches, lighting, musical score, and good acting to create a creepy atmosphere. In the end, it is repressed trauma in a writer's mind playing itself out. It was genuinally creepy at various times. I liked the acting. I liked the characters. It kept my attention the entire time.
I liked it. I also like the added touch of the relationship between Rebecca and Alice and how that is never fully spoon-fed to us.