This book cover blew my mind more the longer I looked at it. Here are some key things that I noticed about it:
The eye is made as the focal point and is in the right space and has the right contrast. The typical place that the eye moves when looking at an image is usually the mid to upper left. This is where the eye was placed.
The foreground is mostly silhouettes with very little extra, but it is used effectively. The two tones for the bear and some other shapes like the clouds add to give depth and shape to each object. (See below)
The text used fits the design feel very well, and even seems to match the sporadic flow of the branches and leaves.
If we look at the direction that everything is facing, it leads our eyes off of the page to the right, allowing us to appreciate the view with the subjects in the picture, however the tiger is facing the opposite direction, which leads us back onto the image.