The app can play an audio clip to tell you if the item is worth to buy or not. It can also tell you the price. This will allow you to use Bluetooth scanner and headset to scan an item, listen to the sound to make the purchase decision without looking at the screen. So you can quickly go through items with less work.
When you scan the item 2nd time, you will hear a voice telling you the price. You can change the voice cue content.
If you put the phone in your pocket, you can enable the lock on the phone screen (Menu -> Lock Screen).