DRM refers to the fact that you can't view Amazon Kindle books on other devices (including your computer), or on other Kindles - i.e. no sharing, the purpose of DRM.
Plenty of free e-books in Mobipocket format show up fine on Kindle.
The Kindle only allows the reading of Amazon DRM-protected content.
Granted the PDF converter seems to have some trouble with graphics PDF's, but for books the converter works very well.
A revolutionary portable reader that wirelessly downloads books, newspapers, magazines and blogs to a crisp, high-resolution electronic paper display that looks and reads like real paper, even in bright sunlight.