We spent three nights over New Year's in the Prenzlauer Berg apartment. For this trip I chose my apartments (also used Airbnb in Milan and Vienna) based on proximity to public transport (train/metro - not yet brave enough to try bus travel in foreign cities) and washer/dryer facilities. Both were good here. Train station with both an U-Bahn and S-Bahn were five to seven minutes away. A slower tram into town was also close by. The washing machine and dryer were top notch and the apartment had washing liquid, a real bonus in holiday season when stores shut for public holidays. The U-Bahn/S-Bahn station also had five bakeries and two grocery stores, so good for breakfast and snacks.
The apartment itself was spacious. Master br was a good size. Second bedroom with two beds up top was also fine for my two boys, 23 and 19. I thought it would be claustrophobic as the twp twin beds are on stilts, but my sons were fine with it. We used the sofa bed for one night, and it was good as well. Kitchen had everything except an espresso pot, but we survived with filter coffee and plunger coffee.
Marcus communicated quickly and well with us. He was also very accomodating in finding extra bedding for us as our daughter joined us for one night and slept on the sofa bed (very comfortable).
Two things detracted from the apartment. First, the place is not really centrally located. Plan for at least 20-30 minutes to get into the centre of Berlin. Trains run frequently but it is 8-9 stops to get to the middle of town. I didn't have a sense that the neighbourhood itself had much to offer: it is not the part of Prenzlauer Berg that is referred to as being the happening area.
Second, the shower is a bath/shower combo (you shower in a bath tub) and that can be a little tight for turning, and can wet the floors a bit).