The App Store in iOS 6 tells you how the applications have evolved over time with the help of Update History

  A novelty of the App Store in iOS 6 that many have overlooked allows us to see how many times the applications available for download have been updated. I'm talking about a section called Update History which can be found on the page of each application in the App Store, and in this section you have listed all the updates made by the developers for that application. The interesting part is that in this section you have listed the changels of each version released over time, so you can see how the application has evolved over the months/years.

  The bad part is that these changelogs are not displayed for all applications, but I assume that by the fall we will have everything available for the 650.000 public titles in the App Store.