You know - most technologies change drastically over time. As a result, I got my hands on an old BlackBerry 950 model from 1998 (the 850/950 series were the original BlackBerry smartphones on the 800/900 MHz Mobitex networks, respectively).
The problem is this: It really hasn’t changed that much. Aside from the color and graphics, the BlackBerry 950 running BlackBerry Device Software 2.5 had pretty much the same applications and functionality as the BlackBerry 8830 running BlackBerry Device Software 4.5!
The Messages, Memopad, Address Book, and Calendar apps had the same look, feel and menus - and the Options screens had most of the same menus (even IT policies and service books). The BlackBerry 950 is from someone who used to work for Rogers and it still has data access - I was able to send a PIN message to my other BlackBerry - and the experience of using the old BlackBerry was uncannily similar to that of using the new BlackBerry.
Now I understand what critics mean when they say the BlackBerry OS is in dire need of an upgrade :-)