This looks like it will be a great product, especially for all the technical pdfs I've built up over the years. Still not wild about the DRM though -- I made the mistake of buying DRMed music that I can't listen to anymore. I'm not going to do the same with books. Anyone else trying to justify a $500 pdf reader? :)
The DRM that Amazon uses is pretty crappy (isn't it all), and is trivial to remove with a Python script available from various file-sharing services. But you didn't hear that from me, I know nothing about it...