Rewatching Doctor Who: The God Complex

Just got to this episode, in my Matt Smith era rewatch. And it's amazing just how much I didn't remember about this. I remembered a hotel of rooms and corridors, and I remembered the ending on Earth. But other than that? Nope, zilch. However it's a strong episode, an intriguing concept, even if it feels a bit like the ideas were stretched too far and a bit repetitively. ( spoilers )