MotionCamera adds a timer to your camera so you can get in on the shot, but is not as easy to use as it could be. Still, you can take group photos more easily than is otherwise possible with the relatively limited photo tools already available on the iPhone.
When you open MotionCamera you can choose the duration of the delay between 0.1 to two seconds. Even with two seconds to get in front of the camera, it often isn't enough for most people. That's why MotionCamera only starts counting when it detects motion. So instead of holding your phone out in front of a bathroom mirror, you can set up your camera, turn on Motion Camera, and pose for your photo with two seconds to spare; Motion detection seems to activate only with objects at least a couple feet away from the camera, too, which gives you that extra time. There are many potential uses for this and it works well, even if the app built around the mechanic offers very few additional tools.
If you use your iPhone camera for a lot of photos and are tired of poor timing causing you issues, MotionCamera offers a solution. It is easy to use yet light on features; but for the one issue it strives to solve, it does a good job.