I know, but it practice it isn't very useful. It is on the wrong side of the phone for how I hold it when taking photos. And you can use it to speed up the picture taking process. Ideally if you pressed and held it, it would unlock, focus and take the picture. As it is now you have to unlock, wait for it to focus and only then can you press the physical button to take the shot.

I also find I get more camera shake when using it, especially compared to pressing the on screen shutter button and sliding off to the side while keeping your finger on the screen.