I stayed in Gustavo's apartment for just under a month while taking online classes and doing remote work. I can't think of a single significant complaint--the place had everything I needed to stay comfortable. The flat was clean, adequately furnished, and had a fantastic view of Mexico City's skyline, during both day and night. Gustavo's building had 24-hour security, too. In terms of nearby amenities, there are several supermarkets and convenience stores within walking distance as well as a Metro and MetroBus station. Very easy walk to the Zocalo and Centro Historico.
If I can stay for a few weeks again next summer, this apartment will be my first choice.