They loved the story and a big reason is in its delivery. I love changing voices for different characters. In the Elephant and Piggie series, I have a set voice for each character. It makes the read aloud more enjoyable and helps students follow along with which character is speaking.
The story takes a darker turn when the Bear denies having seen the rabbit that may or may not have taken his hat. After getting his hat back, he sits happily. The bear claims that he hasn't eaten any rabbits without anyone asking about the topic. The kids laughed and the adults had a shocked reaction.
Jon Klassen makes a reference to his other book (not yet published when this one was released) about a missing/stolen hat when another animal describes a blue and round hat that he saw.
I've noticed that there are regulars who are always interested in any project we may do and there are others that will simply never want to try anything. Some are on the fence and will participate when it's something that interests them and others simply like to observe. I don't want to force any of my students into doing something they don't want to. There are only a few times where the whole class is required to participate in a project, usually the self portraits we do throughout the year.
Some kids loved their hats so much, they wore it to outdoor play, lunch, and almost went to sleep with it on. At the end of the day, many came to me and asked for help putting them back on before dismissal.