flow is a barcode scanning app that scans in real time so you don't have to take a picture and wait for the scan to be processed.
Although Amazon developed its own Price Check application, flow was developed by A9, a subsidiary of Amazon. What flow does that Amazon's Price Check app and apps like ShopSavvy can't is scan codes in real time. The application acts as a live window, picking up information about any barcodes it can get a lock on.
flow scans decently quickly but it isn't instantaneous. There are other applications that are quicker to recognize a barcode but what flow lacks in performance, it gains in a beautiful and full featured interface. After scanning a product, you flow allows you to read full reviews, share the product, and purchase the product right within the app. flow will even give users alternative merchants and similar items, though it will favor products that are being sold directly from Amazon.
flow also adds the ability to scan QR codes. This is great if you're browsing a magazine or see a QR code in the wild. Some codes may take you directly to product to purchase or learn more about.
Overall, flow is a great shopping companion application that has good performance and really integrates into Amazon's database of reviews and products.