First off, as of right now it appears this app(Isis Mobile Wallet) is only available on android phones.
If you use this app to pay, you can get a free 12 oz smoothie or juice at Jamba juice. The offer states valid until April 2014 or until they give away 1 million drinks. Valid for one per day, meaning yes you could go back everyday I guess which is awesome! I have attached the information from the Jamba Juice site.
CLICK HERE for details
Info on Isis? CLICK HERE