The video does a good job of showing the usefulness as well as the limitations of the device.

It's not going to let you do anything you can't already do with your phone. It just makes it quicker and easier to do something. If I want to take a photo, I have to hit the side button to activate the phone, then swipe across the screen to unlock it, then swipe to the page my camera app is on, then open the camera app, then take the photo. With this, you just take out your phone and press the button. There are lots of times when I want to take a picture of the kids doing something, but by the time I get the phone out and turn it on and unlock the screen and open the camera app, the opportunity is gone.

I could see how it would be useful to quickly access features of your phone while driving.