Nina's apartment is a great place to stay. Let me start by saying that my family and I stayed there while I was recovering from a surgery performed in the city, and so we spent A LOT more time in the apartment than most people visiting New York City would spend. That obviously is the lens through which I viewed the apartment.
The apartment is very spacious, probably more so than appears in the listing. It was nice to be on the ground floor. There was a large living room with a comfortable sectional sofa. The beds were fairly comfortable, although one of them had a significant squeak in it. The bathrooms are on the small side, but adequate. We cooked almost every meal for eight days, and the kitchen was very functional. For anyone planning to cook at the apartment, there is a very good grocery store just across the street. There were also a number of restaurants and retail nearby. The location is very convenient.
One thing you should know, especially if you are traveling in winter, is that there's no way to control the temperature inside the apartment. (In summer, there were window A/C units, though we never needed to turn them on to see if they worked; I assume they did.) It was very much on the cool side during our stay (late November). Again, most travelers probably won't spend as much time in the apartment as we did, and there were plenty of blankets for the beds to stay warm at night. You just might want to pack an extra sweater or jacket if you are planning to be in the apartment very much.
Overall, I would very much consider staying here again.