It seems the $25 free credit for buying apps and games from WP store is valid with purchase of Lumia 928 till 23rd June. In case if you have purchased the device already, you need to read below for how to redeem the $25 app credit.
Bought the Nokia Lumia 928 between 5/16 and 6/23/13? Great! Visit http://wp.promo.eprize.com/app/to request your $25 app credit code and learn how to use it.
Also, buyer reviews for Lumia 928 are now coming in at Verizon. The device proudly enjoys 100% recommendation by buyers and 5/5 ratings!! This is based on 46 buyer reviews.