I loved it as well. Some really interesting twists on the old haunted house theme and I thought the use of darkness, especially in the context of a theatrical film experience, was brilliant. The score and use of music was perfect as well, and I thought it avoided the usual cheap jump scares in favor of genuine tension and creepiness. Lin Shaye was great in her role as well.
I have not enjoyed watching a horror film this much in quite some time. Looking forward to the dvd.