We stayed at David's place while in Mexico City for a winter vacation, and it was very nice. The Condesa neighbourhood is very safe and quiet. For any vegetarians or vegans, there are several vegetarian restaurants in the area, while was great for us. David responds very quickly to questions or concerns, and has a helper who seems to be around the property most of the time to help if he's not available.
The apartment was exactly as listed. Everything went very smoothly with check-in and throughout. We had some bad luck in that the water was out for a few days in the whole area due to the city doing some work on the system, but David was very accommodating and let us shower in a different apartment during that time.