Location is good. If you want to be in walking distance of Mitte's bars and eating places then this is great. The flat itself is well appointed but it lacks a lot. The space is wonderful. It's bright and modern and everything you'd expect of a Berlin airbnb but there is much the owners could do to make it better.
The furniture does the space no justice. It's cheap and not even that practical. We had two friends over for a drink and had to sit round the dining table because the two-seat sofa was the only option.
It could be so much better with just a little bit more comfort. A bigger sofa for example or an armchair would make it more cosy.
The wifi is terrible. We called twice the number left on the notes, but no response.

The cafe suggestions left in the flat were great and we made use of those for a couple of days.