Cute!! I love how this book fosters creativity in kids, and it also (subtly) teaches kids that some things are temporary, but that is not always a bad thing.
One of the main things that made this book so great was the illustrations and the use of color. The illustrations start out as completely gray, but by the end of the book the entire town is full of color and life. This was such a smart design choice made by the illustrator because it shows readers the power of making magic out of chalk. Additionally, it shows a progression of tone/mood in the book. This is subtle, but still important to mention.
Lastly, the writing was simple but worked perfectly. It worked so well because the illustrations spoke for a lot of the book. It's clear that the author and illustrator found the perfect balance when producing this book; it's not under- or overwhelming.
Bravo!