If you're traveling to Mexico City (and even if it's your first time there) I'd highly recommend staying at Gonzalo's place. At check-in, Gonzalo was there to greet us in front of his building and took the time to show us the room and the amenities of the building. He also provided a map and recommendations of the city, which was a big help. His place is within a 5-10min walk of several of the attractions and is also not far from the Zocalo.
The room was spacious, clean, and comfortable for all of us. Just note that there is no AC in this building, but it's not really a problem because at night it gets cool enough to open the windows and let in a nice low 70 degree breeze (i stayed over memorial day).
In short, I think Gonzalo and his place are the definition of what a good experience through airbnb is all about. If you're gonna travel to Mexico City, definitely consider staying here!