Some people don't like that the DRM key is based on a credit card number, but it is the least intrusive of the major DRM schemes. The problem at present is that the ebook format itself is less capable than recent ones like ePub. Calibre is about to add eReader to its fully supported formats, and that should tell us just what can and can't be handled in eReader (e.g. how much of ePub formatted gets lost in epub2ereader conversion). Images also tend to be small (see
A Comparison of format limitations based on The Hobbit), but I don't know if they have to be that way.
FictionWise has said that they intend to add ePub support to their Reader and to add eReader DRM to ePub. These plans may have changed now Barnes and Noble owns FictionWise, and some people don't like the idea of two incompatible DRM schemes for ePub.