The apartment was well located for us - who had to be daily at the cultural compound CENART during a week. It is also very close to subway Ermita, which line goes to the historical center. The area is pleasant at daytime, with little places to eat and shops such as Oxxo, etc.. We were told to be watchful at night - which we did by using taxis.
Omar manages the place and is easily reachable, Raul is onsite, and ready to help when needed - but Spanish needed to communicate. The other advantage is that there is more then one apartment, so we were actually several colleagues being together in the same building. One note for apartment 1 - bathroom with shower is an "ensuite" bathroom connected to one of the bedroom, the other bedroom as its own "half-bathroom" (lavabo and WC) but must go through the other bedroom to access shower. If total independance/privacy is needed, better to choose apartment 2, 3 or 4.