This is a gorgeous, spacious apartment (a floor-through in an extra-wide brownstone) in a perfect neighborhood -- near the Natural History Museum and Central Park, with dozens of great restaurants within a 5-block radius. The apartment has all the amenities one could wish for. The hosts welcomed us with goodies from the famous Zabar's, which is nearby; they had various helpful guides to the subway and bus systems.
Two small down-sides:
1) it's a 4th floor walk-up, so you have to be pretty fit
2) To get to the bathroom without going through the first bedroom you have to go down the outside hall and in the front door. Since there is no one else there on this top floor, it's just a minor inconvenience.