This one is really simple. The Halo is a small plastic button that serves as a wireless shutter trigger for your phone's camera. Its only job is to trigger your phone's shutter when you click the button. One function, one result.
My tests with the Halo for my Android phone went smoothly. The company makes an iPhone version called Hisy. You need to install its free camera app, Shutter Panorama, as neither Halo nor Hisy works with the regular camera app that comes with the phone.
Shutter Panorama doesn't have too many manual settings or special features. But the device does a good job in allowing me to place my phone in places other than my hand. I got some nice shots of myself and my dog by putting the phone against a rock in the front yard and sitting a few feet away. It's more elegant than setting the camera's timer and running to get in the shot.