Macro filming, fine focus applications, jib and other situations where remote controls are required.
Tons of features.
Can program 4 focus points.
Price isn't bad when you consider what competitors are charging.
At high motor speeds focusing is choppy.
Programming can take time to fiddle with.
May be unable to use HDMI depending on your cables.
More info at dslrvideoshooter.com/episode-49-aputure-v-control-usb-focus-remote-review-for-dslrs