AVOID AT ALL COSTS!
The flat was filthy, it's clear by the thick layer of dust and spiders webs between the appliances/shelves in the bathroom that it's been a scary length of time since the place has had anything more than a superficial clean. This is also the case for the building outside the flat where there is mould growing around the window on the stairs. The carpet on the stairs is discoloured giving another indication of how long it's been since the place has been cleaned. Indeed, even the garden is overgrown and in terrible condition.
The washing machine does not work, it starts and runs through the cycle but does not clean the clothes nor does it drain the water at the end of the cycle. There is also a foul stench released when it is switched on, which I assume is related to the fact that it doesn't drain at the end of the cycle and has stagnant water sitting there since the last time it was run. The smell will fill the apartment if the door of the bathroom door isn't closed.
The furnishings in the flat function, but are not comfortable. It seems as though the flat has been furnished with a mish-mash of second hand of furnishings that are old, not in great condition and are not comfortable.
The communication was fine initially but as soon as something wasn't exactly as the host wanted it turned aggressive, which isn't unusual judging by the host's response to previous reviews on his various properties that aren't entirely complementary!
When I hadn't left when the host showed up just after 9 AM on my last day, checkout is 11 AM according to my email confirmation of the booking (although the host told me in person 10 AM is the checkout time), the host began sending messages that were at best coercive, verging on threatening, including instructing me not to leave a review. Airbnb have been notified.
This culminated in the host filing a request for reimbursement for €700 claiming damage to a wall that was A) There when I arrived at the property and B) A cosmetic mark on the wall. He also complained that I had a second guest, which is bizarre given that I asked for a second key for a few days as my husband would be joining me, and he told me he didn't have a second key to spare but that we could hide the key for each other outside the building.

If you have the option to stay anywhere else and avoid this host and this flat, do so! I now understand there's a reason it was so much cheaper than virtually every other place in Berlin at the time I booked it, but still represents terrible value.