The following article from the Prism-v2 documentation contains the breaking changes between Prism-v1 and Prism-v2
Upgrading from the Composite Application Guidance for WPF - June 2008
If you do not mind, I will briefly share my own experience migrating from Prism-v1 to Prism-v2. Most of the changes we performed to the
code were pretty quick, and we were able to get the application running really fast.
However, we spent some time with the Unit Tests with some considerable changes in the Region/Region manager mocks, which might have been
faster if we’d have used a mocking framework in the first place.
I hope this helps.