Very useful I have just moved to Vienna for my work. I have lived in Germany previously and they all laughed at how formal my German was. The slang part makes learning fun. However it eats your battery.
THIEVERY! Paid for it a f....n 50€ and it doesn't even load! LAST UPDATE WAS 2014. Same thing on iOS! Kick yourselves out of the appstores!
I don't know what it can do, but I know what it can't - download. Tried 3 times.