Canon's press material for the EOS 5D claims that it "defines a new category of DSLR", although we're not normally too concerned with marketing talk, this claim is clearly quite accurate. The EOS 5D is unlike any previous digital DSLR in that it combines a high-resolution (12.8 megapixel) full-frame (35mm size) sensor with a relatively compact body (slightly larger than the EOS 20D, although it feels noticeably "thicker" in the hand). The EOS 5D is designed to sit between the EOS 20D and the EOS-1D professional digital DSLRs, one important difference compared to the latter being that the EOS 5D has no environmental certification. While Canon doesn't specifically refer to the EOS 5D as a "professional" digital DSLR, it will clearly appeal to professionals who want a high-quality digital DSLR in a lighter body than the EOS-1D. It will undoubtedly appeal to current EOS 20D owners as well (although let's hope they haven't bought too many EF-S lenses...).