Olga's apartment is ideally located between a few train stations that will take you from the UES towards midtown and further. It is a few blocks from Central Park, so it's easy to walk over to the park and then through the park towards midtown or across to the UWS.
The apartment itself is well kept. The room had no noise pollution, so after my 20-hour flight, I could fall asleep peacefully on both nights that I was there. The room is a good size, and the bed is very comfortable.
Olga and her daughter (I only met one) are incredibly friendly and hospitable. I highly recommend staying at their apartment if you are visiting New York.