My stay in NY, was perfect. Jeanine and Jimena were very welcoming. The room was pretty small, but I was aware of that when I booked, and yet, the apartment was large and I could use the kitchen or the living room as I wanted. The location is great, really next to the subway and not far from Central Park. However, you'll need a MetroCard if you want to go Downtown to visit. Harlem seemed to me totally safe: I never felt endanger. When I had needs, the two roomies had answers. They were very convenient: we never had problems for the sharing of the bathroom, and there were no problems of noise at all.
In short, this first stay in NYC was very nice, and I am pretty sure I would go back at J&J's if I ever came back soon here.