Like many other horror films, it is very voyeuristic and sexualised. There are several shots where you suspect the director was standing behind the camera, filming the sex scenes with a great deal of personal interest invested in watching Hilary Swank get naked or engage in intercourse. Hell, many of these shots border on or seem like they are leading to tastefully done pornography (although I suspect that's an oxymoron for some people).
One niggle that I did have was an issue with the home monitoring system that Swank (I forget her character's name; it's not important anyway) eventually gets around to installing. Why does this system not automatically send images that are worrying to the police or the company themselves? It's left to Swank herself to watch the footage back, and of course she neglects to do so at a point where she could actually do anything about the events.
I would suggest this as a good movie to watch alone at night to feel the full effect of the horror, as the whole point is to create paranoia about whether or not you're ever truly alone in the house. It's not as effective during the daytime with sunlight streaming through the window, but it still managed to create a tense atmosphere and scared me, which I feel says something about the quality of the film and allows me to recommend it.
The Resident is out on DVD and Blu-Ray July 4th.