I thought "The Strangers" was a pretty good horror movie. The three creepy people in it are all, well, creepy. The director does a really nice job of making you feel uneasy everytime these masked people were on camera.
There were several scenes where you would see a masked person in the background unknown to one of the main characters. It's not really a common technique used in a lot of horror movies, but it's quite uncomfortable to watch, but also so very cool!
Unlike most movies in the horror genre, it spent less time trying to scare you with unexpected noises & sudden occurances, and focused more time on making you squirm in your chair with obvious, but unsettling visuals.
It allows you the chance to think, "Oh my god...uh-oh... no... no... nooooo... eek!" instead of trying to make you jump out of you seat with a bunch of sudden out-of-nowhere scares and false alarms.
I didn't feel there were any real surprises in the story so I think, if there was one thing preventing it from being really good, it would be that.
There's nothing here that makes you think that there is a sequel in the works (which always makes for a better movie when they aren't thinking past the task at hand), and even though there really isn't any reason for another, there isn't any reason there couldn't be either. In the horror genre, as long as people might pay to see a sequel, there usually is one.