Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Third Person (Limited Omniscient)
For the most part, we experience the bizarre events of this story along with its protagonist, John Unger. We get to hear his thoughts, his perspective, and we generally aren't privy to things outsider of his own range of perception. Because of this, we see the Washington Estate through the eyes of an outsider. The estate is painted as a strange, unknown world because that's what it is to John Unger. Consider how different things would appear if we heard the story through, say, Percy's eyes.
Though we do stick to John's perspective for most of the story, there is the occasional moment where the narrator breaks through and provides us with his pearls (diamonds?) of wisdom. When the village of Fish is described, for example, we know that this is the narrator speaking, not a glimpse into John's thoughts. Another important passage is the slightly cryptic message about youth inserted about halfway through the story ("it is youth's felicity as well as its insufficiency that it can never live in the present" [5.3]).