What is the author's style in After Ever After by Jordan Sonnenblick?

The story is written in the first person and is extremely informal. The story occurs mainly in chronological order with one significant exception. The second chapter begins with Jeffery's eighth grade graduation. The timeframe then changes to the beginning of the eighth grade year when Jeffery begins an English assignment in which he's supposed to write about "the most annoying thing in the world." He outlines one of the biggest issues with being a cancer survivor and the next chapter meshes smoothly into that writing assignment. The remainder of the book is presented in chronological order.