Regardless if you're using Windows Mobile device, Palm, some other device, or even the iPhone, there's a PDA that was built from the ground up, not borrowing from any other GUI. It was designed to do exactly what you'd expect, assist you -- naturally. Email, fax, print, beam. You name it, it did it.
And then Steve Jobs killed it. And no company (not even Apple) has made a PDA that can rival the ease of use, simplicity, and power of the Newton.