Fantastic stay with great hosts! was initially worried on first arrival due to some graffiti on nearby walls (it was dark as well) however the area was completely safe. We saw children being sent out for errands for their parents!
With regards to the amenities, the rooms were rather plain, the exception being the large master with a balcony.
The bathroom likewise was on the smaller side, but perfectly functional.
Towels were provided, but you are expected to reuse (which is fine)
Tap water is safe and fine, though be aware that some of berlins water is hard water and can cause throat irritation.
Only real complaint we had is there is no light outside the door. There is a motion activated light on the floor below, which helps going up, however going down you are sometimes in complete pitch blackness.
Over all though, fantastic stay!