Navigation is complicated. Attractive navigation bars located at the top and bottom of most pages link to the other subsections of the particular section you are currently in, as well as to the table of contents. However, the table of contents is the only place where you can access all of the site's major sections, and each section's subsections are accessible only after you have entered that particular section. Important bits of information are repeated for the benefit of the users who prefer to wander through sites. However, most of the subsections contain linear narratives, which need to be followed from beginning to end for maximum impact.
Readability is for the most part excellent.
Both secondary and primary sources are used and properly cited, and links to a full bibliography are provided. The physical location of the original material is provided. I would have appreciated larger versions of images or selected primary source materials linked to image or text files of the entire source so that I could examine the original in detail. According to the site's designers, a curriculum guide is under development. Assuming that this guide appears, this site has much promise for elementary and secondary educators interested in challenging their students' understanding of historical evidence.