Overall, it's downright one of my favorite games of all time. Sure, it may be a visual novel, but the overall concept of the game is just so damn interesting to me. While it may lack in the gameplay department, it nails in terms of story and atmosphere. The game does take a long time, and I mean a LONG time before anything actually scary happens, but when it does happen, it hits you like a damn freight train and doesn't slow down until you reach the end.
One thing that has kept the game up in popularity for as long as it has is easily the modding community.