This new program will mark Apple’s first expansion of pre-release iOS version testing beyond developers and employees within the walls of Apple’s Cupertino headquarters. For the past few Mac OS X releases, Apple has provided early copies of the system to employees, which has helped Apple identify bugs before public launches.
iOS pre-releases have always been limited to developers and select corporate employees, but Apple's expansion to retail employees is most likely is an effort to improve the software quality of iOS. Apple greatly expanded OS X's testing pool with a public beta of OS X Yosemite last year.
Hopefully the expanded testing improves the software quality of iOS 8, which has recently experienced criticism