During usability studies at Chomp, we learned that people search for apps by function in their browser. Once they found what they were looking for, they would type the app name into the search box of the App Store. The basic list of results forced them to pogo-stick, if they wanted to learn more about an app.
In addition to a cleaner and more simplified design, we followed the visual metaphor of cards that we established at Chomp.
For both the App Store and iTunes, we introduced hints and suggestions to make it easier and quicker for people to find what they were looking for.