Although the building is not perfectly clean (it's an old one, but with the advantage of being very Newyorker, in a good sense :)), Casper's apartment itself, in which we stayed 11 days in December, is very pleasant to live in, perfectly clean and convenient, and perfectly located in a quiet street, close to several bus and subway lines, as well as to all types of stores and services. We really had a wonderful stay there.
Casper managed to facilitate our stay, agreeing for an arrival late in the evening as our plane was delayed, as well as for a few hours late departure, as the apartment was not rented the night after. He also accepted our daughter to join us for a few days, sleeping on the sofa. We warmly recommend his place.