One of the things I seem to notice with pdfs, or other electronic versions of print media, is that it makes it hard to actually mix words and pictures. As a result, the "picture" books don't often resemble the picture books I'm used to seeing for this age group as the images come before or after the text, and not on the same page with it. Whether it's that way by design, or because of the nature of the media, it loses some of it's effectiveness, I think, in it's storytelling nature.
However, this is merely cosmetic. The story itself has a good message - worry too much, and you can make yourself have a nightmare! It also comes complete with a guide of talking points.
The true test will be what my niece thinks of this story!
I'll add her reactions when I've had the chance to have her read the story, so keep checking back!