As the book goes on it also gradually fills in the backstory to explain how the lead character came to be there, it quickly becomes apparent that there are many things he is ignorant of.
Did you see a reason for the amnesia the House induces, apart from a device to allow the story to happen? There might be a subtle thematic tie-in with the way the House "remembers" the real world, but I couldn't satisfyingly make it work, which was my only real problem with the story (but since the whole thing hinges on his amnesia, it's quite a big one).