A major change for Postbank customers should not be necessary. For the new application, the Access remains the same: the Postbank ID and login password remain the same. Customers only need to activate the BestSign procedure in the new application.
This is exactly why the old Financial Assistant app is required. This enables the security procedure in the new application. You should only remove the Financial Assistant from your smartphone once you have done so and the new app is working.
But the new app fare poorly with Postbank users (1.2 stars in the App Store, 1.4 in the Play Store). The two main points of criticism: technical problems, for example when activating the BestSign procedure or when displaying the account balance, and a very limited range of functions. Although transfers are easier to perform in the new application, many other functions such as search or filters have been removed.
Postbank only states that it wants to expand the functionality of the new app in the future. Oneshould help users change.