To make it short: the flat is just as nice, as shown on the pictures.
I stayed for over 2 weeks and was happy with it throughout that time.
Be aware that the flat is only being rented out and no one actually lives there.
The kitchen is well equipped!
The flat is perfectly located in Friedrichshain and only a 10 minute walk from Kreuzberg, 10 min by metro to Alexanderplatz.

Everything went fine concerning the handover of the keys; it's a little team that looks after the flat.