The change log for the app is pretty short, but what it does say is very nice. The change log reads in full: "Fix for the 1-2s delay seen when swiping down or up to unlock from Active Display screen." That is a pretty big fix if it really does get rid of that delay. A 1-2 second delay can get pretty grating over time.
Of course, the update is only available for new Motorola devices with AMOLED displays, which means the Moto X, DROID Maxx, and DROID Ultra. The DROID mini, and Moto G both use LCD displays, and so don't support the Active Display feature. If you have a compatible device just check the Play Store for the update.
Download: Motorola Active Display
source: Android Central