In short, I am not certain why this book received a Newbery award. I would consider it a "beach read" for adolescents. Literary value? I felt like there were too many stories in this short work, none of which were fully developed.
One of my students did read it during the school year. From what I recall of the conversation, she thought it was fine. Nothing exciting. She was more excited to learn that "Turtle" was the main character's name. I don't recall her giving much more detail.
The novel was just "OK" in my opinion. Like I said--a beach read.