Depth of field On the downside, digital camera lenses while small and fast have a very deep depth of field even when fast. This may be what you want sometimes but it can also ruin good portrait work and other types of shots. In the future digitals will be able to simulate short depth of field. A little bit today, and more in the future, digitals will have smart lenses they understand fully. They may also correct for some types of chromatic aberration and other problems that simple lenses need correcting elements for.
Simpler lenses means cheaper, lighter and more contrast.
12 bits per pixel rather than 8, and a way to use it through a CCD-RAW style format. The upcoming Canon SLR Digital comes close to meeting this. Those are on the must-have list. A fast interface to the computer, USB or better 12 megabit IRDA to avoid cables. A great lens able to fully resolve, with a wide range, or interchangeable lenses or quality lens add-ons.