I have used lots of different devices over the years.  One day I may actually try to list them out, but even then I am bound to miss a few.  I have used devices from Palm, HP, Compaq, RIM, Apple, HTC, Motorola, and Saumsung in just about every form factor available.

The main lesson I have learned from all of these devices is that I like buttons.  I like buttons that can be remapped.  I like the buttons even more if they can be mapped with both a press and hold action.  I like devices that have a physical keyboard (lots of buttons) that allow you to launch programs from the keyboard.

On my Treo Pro, I have the button on the left setup so that when I press it, it emulates Alt-Tab so that I can easily swap between applications that are running at the time.  This one button saves me countless other button presses or touches on the screen and saves a lot of time.

I really really like buttons.  Now, time to find the buttons on the coffee pot.