Shake Camera doesn't need additional shutter button, and supports for all kinds of selfie stick. It can shoot automatically after you shake your device. (Camera will shoot when timer bar reach top)
If you are not ready to shoot, you can just shake the phone or touch the screen to cancel. And shake again to start the timer when you are ready to shoot.
Shake Camera is very suit for using selfie stick (Shake Camera will make it shoot automatically). Of course, Shake Camera is also suitable for normal shoot condition.
To save time, after you shot the image, you can Shake your phone to save the image and begin next shoot, you don't have to press any button. Or you can set auto save mode to disable preview photo in setting page.
You can set the interval of the time you hold phone motionlessly to shoot. (2 second / 4 second / 6 second). Besides, you can also set camera relative function in setting page, such as switch front / back camera, flash turn on / off, self timer, special effect, camera resolution...
After you finish your shot, you can save it, or share it to your friends directly by press share icon. You can also browse the photos you took using the its photo browser.

p.s. The default camera is front camera, if you want to use back camera, please click camera switch icon in setting page.