It's the magic of Pearl's pearl.
I must to confess that by the power of habit I was always searching with my thumb the trackwheel when I started playing (as usual) with Pearl's keys and buttons. The magic of pearly trackball convinced me that it suits better the consumers.
I never took pictures so easy. It takes just a gently roll up or down to zoom in or out with the camera. And just a quick press will take a picture holding the Pearl only in one hand. On top of this the applications menu navigation is much easier. And guess what was my first Pearl accomplishment. While playing with its buttons in the store I was surprised when I took my first picture by mistake.
My advice for Pearl users is don't keep the eye on the pearl since it keeps an eye on what you are doing and tries to serve you better. I find this approach kind of similar with the keyboard suretyping. Blackberry use is about reading your mind.
Picture taken with Kitchener City Hall's Wheels as a background.