We visited Hermann's apartment the first week of September with an group of 6 friends from the Netherlands.
The stay and the apartment was great and spacious. The kitchen was great , fresh coffee-beans grinder and all A-branded and of good quality appliances.
The location is good, there is an Tram on 2 min walk and an U-Bahn on about 7-10 min walk.
There is an nightshop (Späti as the Germans call it) very close and an medium large supermarket on about 4 min walk.
We enjoyed the contact and kindness of our host Hermann, he is an relaxed and funny guy who arranged everything perfectly and beyond our expectations.
I would definitely recommend his apartment to friends if they plan on going to Berlin.