Saw this on prepaidcompare.net:
Cricket users can use the app to view static ads, lockscreen ads, video ads, and offer walls. Rewards can be applied to your Cricket bill, or to gift cards. Cricket is over-priced for my needs, so the reward earnings would have to be very high for it to make sense for me.
Cricket did a trial of this earlier, although I'm not sure if it was the same app or ad vendor, and it seemed to get some traction with customers.