Though I didn't meet Charlie, communication was sufficient for an efficient check-in/check-out. A generous host leaving many snacks to welcome the guest. The apartment is spacious and clean on a pedestrian-zone alley, 15 minute from Osmanbey metro mostly uphill/downhill. It's a one-bedroom (photos are accurate depictions) one floor-up with no elevator located in the upscale area of Nişantaşı. Very good WiFi. It's on top of a cafe and there are several restaurants in that alley. Noise level, well into the night, is on the high side, though I had the main door of the balcony ajar for fresh air and I can tune the noise out. I found many bus lines to be a better transportation option to move around the city. The metro was a convenience low-cost especially for a ride to Atatürk airport.
Weather was cool during my visit in late April so I didn't try the air-conditioning or heating. The all-marble bathroom/shower was fancy with good water pressure. The only inconvenience was the too-dim lighting in the bedroom and bathroom.
Overall I enjoyed my stay and would recommend the apartment for visitors wanting a different Istanbul experience (more European).