A reader said that the example images looked "blurry" when switching from the grid view to the loupe view. There are two reasons why this may happen.
Lightroom can take several seconds to generate a full-frame view of an image while switching from the grid's thumbnails to the loupe view. In the interval, the image will look somewhat blurry, and you'll see a circling icon in the main frame that says "Loading". That's because the download examples do not include previews. I left them out to make the example files smaller/quicker to download.
The other reason is that not every example image includes a full-resolution version. I included the fatter files only when the exercise/chapter deals with a topic where you'll need/want a full-resolution version, such as Chapter 9 (Developing Images). Working with images from Chapter 5 (Organizing & Reviewing Images), for example, you don't need full-resolution versions because the chapter focuses on simply learning how to organize the images, not making up-close corrections. Again, this was done to keep the download slimmer/speedier.