What is the author's style in Mark Twain's Letters from Hawaii by Mark Twain?

Much of the content is written from a first person, autobiographical perspective. When there is a cohesive narrative, the narrator and protagonist both are Mark Twain. Letters are written in the past tense, as if the author were relating events from his own experience. The narrative occasionally gives way to essay format, whereon Mark Twain addresses a topic and offers his opinion. The narrative portions are written with an eye toward entertainment. The essay segments, intended to be either informative or persuasive, tend to be more function-oriented.