I saw the trailer to Mirrors when it was first released at the theaters, and thought to myself, "That movie looks horrible." So you're probably wondering why I watched it, and the answer is because I saw a TV commercial that the horror fan in me couldn't pass up (without spoiling too much it involves a girl and a jaw). I'm glad I did watch it because this movie was great.
Now, I don't mean great in the sense that it rivals Lord of the Rings or 2001: A Space Odyssey, I mean great in that it's a mystery/horror/thriller that is not meant to be taken too seriously; it made me jump a few times, but really kept me guessing until the end. I was literally on the edge of my seat for most of the second half. The kills were all very cool (see note), though the plot and the "fight" at the end was...uh...different. The ultimate ending didn't have much explanation, but I think it was pretty neat.
Note: I watched the unrated version, I don't know what's different about it but it's likely a few (violent) scenes were extended.