Our family of three (two adults and a two-year-old) really enjoyed our stay. The location is convenient two the 2 and 3 subway lines a few blocks to the south, and other subway lines to the north. It took us about 30-45 minutes to get to most places in Manhattan that we wanted to visit (e.g., Lower Manhattan, One World Trace Center, Times Square, Central Park, etc.). The street on which the apartment is located is quite nice, although the greater neighborhood is undergoing transition. The apartment is just a block or two from the Brooklyn Children's Museum, which we wanted to visit but did not have time to see.
The apartment itself is spacious and nicely decorated, with a lot of natural light. We appreciated the full kitchen (including gas stove, microwave, and refrigerator) with plates, utensils, etc. Our hosts also stocked the fridge with basic essentials, such as milk and butter. The bedroom is located in the back (away from the street) with a door exiting into a private patio area. Our daughter enjoyed running around the patio when it was sunny. The bedroom includes a closet with a washer and dryer (soap provided), which was very handy. Finally, the bathroom was nicely appointed, with a great shower (tall and good water flow).
Although we did not use them, there was an air mattress and a couch that could be a bed. The apartment is large enough to comfortably hold at least four adults, or a family with additional children.
I would not try to park in the area--like most of Brooklyn, parking is extremely limited. It is much more convenient to use mass transit or bike.
Alex, Nils, and family (including young puppy) were very pleasant, and Alex provided good tips on local info. Would certainly recommend this apartment as a home-away-from home while visiting Brooklyn or Manhattan, particularly for a family!