I really enjoyed my stay in CDMX. Marlene was very responsive. The apartment itself was very clean and well-kept, although I do agree with other reviewers that a mattress pad would be helpful. The wifi worked really well and was very fast. The AirBnB was well located- not far from the Zocalo, Passeo de Reforma, and Palacio de Bellas Artes, and other major spots. I generally felt safe, even though I was traveling on my own. Basically as long as you stay sensible and don’t draw attention to yourself then you should be fine. The AirBnB was very secure- you had to be buzzed in, needed a key for the elevator and there were strong locks on the doors.
One note- the reception staff was very friendly and helpful, but they spoke very limited or no English. Obviously, it’s not an English speaking country, so that’s fine. I do recommend learning at least some simple phrases in Spanish beforehand. This will help a lot in the city itself, not just the apartment.