My biggest concern regarding Prime is the keys inventory.
The scrolling speed is far too slow and feels completely unnatural compared to any other Android app. The application should be able to scroll the screen with the same speed as the input gesture. But actually this is not the case, the scrolling speed is limited at some point, which is totally annoying.
On the other hand the horizontal scrolling between the other items in the inventory sometimes is too sensitive and quite often I have difficulties to select the wanted item.
Last point: it would be very nice to get into the keys inventory with one touch from the main screen.