(When I say 'digital organizer' I have in mind only its primary purpose (like the old ones).)
* Digital organizer on which you worry about batteries once in 6 months at most.
(which implies: simple monochromatic LCD, limited back-light , non-rechargeable batteries with great capacity, memory limitations (but 2MB or even 4MB at least))
* Full QWERTY hardware keyboard (ideally entire standard PC keyboard layout)
* No cover lid (implying scratch-proof display and keyboard (the kind like on those credit-card-sized solar calculators if you've seen one ( http://images.virtualvillage.com/001495-001/001.jpg ), but with slightly raised buttons which make a small click when pressed under that scratch-proof membrane))
* Screen with fair resolution so that a lot of text is viewable at once (maybe 32x8 characters or even 64x16)
* Unlimited text entries (for example CASIO models had 384 character limit per data entry)
* All the standard functions (and possibly ability to add new functions), quick, reliable, and all of them readily available through hardware function buttons
* USB connection for easy and quick memory backup and editing
