These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: House, the sentient Asteroid, is a creature that has butchered hundreds of Time Lords unlucky enough to land on his surface and stitched their bodies into subservient playthings (also took over the mind of an Ood to act as a servant), then hijacked the TARDIS for use as a new body, leaving the Doctor behind to die on the collapsing remains of his old body - and condemning its playthings to die without his influence, to boot. House then decides to use the Doctor's companions Amy and Rory as its new toys, forcing them into the labyrinth of the TARDIS corridors, torturing the two of them with nightmarish illusions, and taunting them with its catchphrase: "Why shouldn't I just kill you now?" House is a being that operates solely according to its sadistic principles of amusement and enjoys torturing whoever is unlucky enough to fall into its grasp. Death might be certain, but House makes certain that when the end comes, its victims will wish for death.
Amy has to think of the things that each part of the password represents. For "Delight", she recalls her wedding with Rory.
Nightmare Fuel: Okay, let's skip right over whatever it was that was supposedly happening to Rory during those millenia he was trapped alone inside the TARDIS (although the phrase "They come in the night. They come every night and they hurt me," is right up there with the scariest lines in the whole show). What about the cabinet that was absolutely crammed full of recordings of the terrified last cries for help of dozens, maybe hundreds of Time Lords, none of which were ever answered?
Tear Jerker: The TARDIS' goodbye — and in-universe to boot.