Both the PRS-505 (with latest firmware) and PRS-700 fully support the PDF and EPUB standards, both open access and protected with Adobe ACS4 DRM, which means commercial eBooks can be purchased from hundreds of retailers and borrowed from thousands of public library systems. To me this is table stakes interoperability for a device worthy of my investment and attention. As a consumer, lock-in sucks. Sony has their own Connect eBook store, which they have been steadily improving, but I am not stuck with it as my only choice.
Emphasis added by me.
Let's see ... with the abominable Kindle you can
1) Buy eBooks from one store: Amazon
2) Borrow eBooks from zero public libraries
Yeah, but ain't that wireless worth being locked in and isolated on Amazon's Alcatraz?
The Sony Reader: For People Who Like To Read More
Kindle: Rhymes with Swindle!