We were staying in Maximilians flat for a week with our two kids.
Communication with Max was always very friendly and promt.
The flat is amazingly located for sightseeing in Berlin as the subway entrance is right in front of the door.
Getting the keys appeared to be a bit adventurous, but turned out to be easy and very convenient.
The flat however was unfortunately not as described.
No towels, filthy crockery, missing plates and cutlery, the kitchen and dining room/living room were not equipped with the furniture shown on the pictures. For the price we paid, I was frankly speaking expecting more.
To my impression, the owners do not really care for the condition of their flat, as things are broken, an walls need some maintenance.
All in all the flat is more like practical and functional, rather than cozy "retro chic" as it appeared in the advert. So we would recommend the property to people who don't care so much for the accomodation itself but more for staying somewhere central in Berlin.