It's a nice, cosy and clean place, at a great location. It was perfectly quiet and from there it was very easy to go anywhere in Berlin, either on foot or by taking a subway. We came during a cold spell so we were glad to see the heating working really well.
On a different note, we found the hairdryer not working at all and when we politely asked Ruth if we could maybe borrow another one, we didn't get any answer at all. I understand she doesn't speak English but some answer would really be expected. Also, the bed is not too comfortable but nothing terrible. Just be aware that it's not a double bed, there are two beds pushed next to each other.
Oh, and the wifi, of course. We expected it to be bad, reading the reviews, but it is beyond bad. Nobody comes on a vacation to be online all the time but you expect in 2019 at least to be able to normally read some news in the morning. Forget videos or heavy photos.
So, all in all, we did have a good stay but it could be better if they improve just a few things.