It’s a text-heavy site: it has no images whatsoever, except for the logo. I didn’t want to bother with doing a Flash site. My goal was to have the special effect (fading) without using Flash. I saw that it was possible with AJAX and was thinking that it’s possible from page to page.
I understand concerns about usability, but it’s an extremely clean site: white background, sans serif black text. I prefer a fade aesthetically because when someone clicks on a new section, it is a “jarring” transition: suddenly text appears.