Only somewhat useful
Berlins subway stations are unmanned and confusing. You need help, but this app isnt it.
The app is built on data taken from a static map. I know this, because it has directed me to take line numbers that no longer exist. Also, it wont give you a platform number or direction to stand at. So it gets you to the nearest station then youre on your own.
In order to figure out which way youre going on a line, you need to read an electronic display which usually (but not always) shows the last station on your line in your direction of travel. The route info youre given by the app omits this crucial detail. When you click on the map to display your route, it zooms right in to the first station. So you have to manually zoom and pan to even see your route, and then follow the colored line to the end in both directions to see the station terminus name past your destination so you know what train to get on!
Get a current paper map instead of this app. At least the info will be current.
PorteñoCanuck about
Berlin Subway: S & U-Bahn map, v1.3