Kathrin's apartment was great for our group of 7! Convenient location, lots to see and do in the neighborhood, walking distance to the UBAHN. The front bathroom was a bit tricky with the layout.
Things to be mindful of, but not deal breakers:
We had to make sure not to get water all over the rest of the bathroom floor when we showered and vent out the bathroom every time to avoid it from getting mildew, so be mindful of that. We also all had 1 towel for the entire stay, so had to be conservative of that as well. Otherwise, great place to stay!