We were four adults and three small children (ages 1-3) visiting Berlin for a weekend. We enjoyed our stay. Apartment was roomy and clean. Enough towels, linen, dishes, toilet paper, soap etc which was nice. Kids enjoyed toys. They also arranged us two baby beds and a baby chair. Washer and dryer were great! If bigger croud, one toilet could be crowded.
Apartment is on 3/4 floor so lots of stairs to climb and not so handy with strollers! We didn't like the area that much but the connections were ok. Very easy to take the TXL bus from Tegel airport (20min) and metro, bus and train stations really close. About 30 min to Alexanderplatz. We would recommend!