PDF and postscript have no ability to reflow text. That is a huge limitation for reading the same content on mobile devices, tablets, and PCs. This has been discussed before here: http://news.ycombinator.com/item?id=1394134
I think its somewhat sad that Knuth solved this problem in 1978 and we're still dealing with terribly formatted web pages and ebooks over 30 years later.
My Android has a pdf reader. It renders anything that fits within its memory constraints easily.
How is Kurzweil Handwaving, Inc. going to substantially improve on that? Scale it up to a nice sharp (PixelQi?) display, put it on a tablet -- presto.