What are the main stylistic devices in "No Longer at Ease" by Chinua Achebe?

In No Longer at Ease, author Chinua Achebe consistently adopts the third person omniscient point of view, but much of the novel is driven by dialog in the first person. Achebe uses modern British colonial English with American spellings, and each of the non-European characters slip between "proper" English, Ibo, and various forms of pidgin.