This novel is told in first-person narrative. That is, Holden is telling the story. However, the viewpoint is different because although Holden is narrating the story as a reminiscence, the author's views come through and he is an older, mature man that inserts his viewpoint of things into the narrative. The story is written in stream-of-conscious style. That is, the thoughts are narrated as they pop into the narrator's mind. He just tells what he is thinking, so his thoughts often seem random and disorganized. The chronology of events seems to go back and forth as the narrator remembers events that have happened to him in the past.
The language is supposed to be that of an adolescent, so the language is often informal and rough. Holden says "and all" a lot and "really" - rather like a modern day teen might use the words "like" and "actually" frequently interspersed into his speech. He uses the word "hell" a lot as a simile to emphasize things, i.e. "ugly as hell" and "old as hell" and "helluva". He is also fond of words such as "moron" and "phony." The angrier Holden gets, the more he uses "goddam" as an adjective. For this reason, the novel has been banned in many schools. Nevertheless, it is one of the greatest novels in American Literature because the language and style Salinger used made Holden seem like such a regular teenager.
Read about it here on eNotes.