The good thing about German is that it's not hard to get to B1 level, however things start getting harder after that. I, for one, am stick on the B2/C1 plateau for a long time, and lots of expats struggle with it.

I would love to see how you tackled the Adjektivdeklinations issue in German. For me that has been an achilles' heel, and there's simply no easy way around it.