Please note that this list is what we're currently aware of that has been reported as an issue in version 6.5. We'll keep this updated with issues whenever we have confirmed a report of an issue.
Mobile Forms iOS App
Investigate and Fix Issues with Loading 6.4.5 eForm Templates with Calculation Regions in iOS 6.5 [SB-478]
The iOS 6.5 app will crash if you attempt to load a Form that has been upgraded to the eForm 6.4.5 version and has at least one Calculation Region in it.
Downgrade the eForm version to 6.2 or below. If you must use eForm 6.4.5 version, we will need to write a script to perform the calculation in a Label Region instead of a Calculation Region.