I like how the artist began with the design concept of a guitar but strayed away from that and created a scene with it. I think the simplicity of the piece allows the guitar to still be seen. I love how you can see both the scene and the guitar easily.
This book cover shows excellent figure ground/negative space. The contours formed by the position of the fox serve as the shape of a boy, I'm assuming "Peter." This empty space also creates a wonderful focal point for the book title to nestle into.