We stayed 3 nights here in September, 2016 during the hottest week over the century in Berlin. The weather outside was +32 degrees, extremely hot. Therefore the main disappointment with the hotel was that none of the rooms have air-conditioning and even the fridge... So it was impossible to stay in the hotel during the day - very hot, no ventilation even with windows opened and no ability to have cold water in the room.
Apart that, the hotel is nice, spacious rooms, simple but elegant furniture, quite good breakfast.
But do remember that apart from TV and stereo-system for ipod the room has nothing. No safe, no air-conditioner, no fridge, no kettle, ...