Wow, cool. Maybe you can post a few sample pages to give us an idea?
I hope you keep the digital version updated with the library, though, as it's undergoing some changes right now. For example, the following (very commonly seen) code creates a memory leak:
img = new Image(256, 256);
Graphics g = img.getGraphics();
I've introduced a (temporary) workaround in the development branch until we can fully resolve the issue.
Slick's API might also lead to some bad practices (e.g. like creating new FBOs during rendering, or making non-power-of-two images, or using frequent calls to Image.draw instead of drawEmbedded). Hopefully you've addressed those things in your book?