The flat is really well located in Mitte, and very close to an S Bahn station (less than 5 minute walk). It can be noisy at night due to how central it is (but due to the heat we did have the balcony doors open). You could sleep 5 here using the sofa bed as a double bed. There are lots of food options nearby.
The room is a quite souless airbnb - it is an apartment just used for airbnb, but it is very clean. Towels and bedding are provided and that is all. There is a washing machine which was great appriciated as we are in the middle of a longer trip. We thought it was a bit cheap to only leave 2 only toilet rolls for 4 people for 4 nights.
We had 1 fan but a 2nd would have been nice as we were 4 people in 30 degree plus heat.
The street is home to a small red light dstrict at night - expect to see women waiting in the doorways the street. If this bothers you I woud book somewhere else. The area felt very safe however.
Elena communicated with us very well and got back to us very quickly.