The apartment is even more charming than it looks in the photos, and there are nice touches like fresh flowers, bread from a nearby bakery, and local soaps placed throughout the apartment, all of which create a boutique hotel-like atmosphere. The apartment is also generally very clean. Also, a large container of bottled water is provided, which is more than enough for a few days. The apartment tastefully blends modern and local styles.
I do feel like it should be made clear that the entrance to the apartment is off of an alleyway. The alleyway and the neighborhood were generally quiet, but I do think some people may not feel absolutely safe at night coming back to the apartment, especially because there's not much activity. Just to be clear, I didn't experience any problems, so it's a matter of personal comfort. I think the host should provide a photo of the entrance for the sake of transparency.
Also, as other reviews have noted, you can hear creaks and plumbing noises from the other residents in the building during the night and in the early morning, especially because the bed is adjacent to the interior courtyard. I always bring earplugs when traveling, so it didn't bother me.
The courtyards are very enticing, but be careful about mosquitoes coming in, which is probably less of a problem during the dry season. Because you can't really open the windows or doors at night, I found the apartment to be a tad stuffy at night. It appears that screens on doors and windows are not common in Mexico City.
Finally, I would be remiss for not mentioning that the wifi did not work for my entire stay (I connected to the router but there was no internet). I informed Maria immediately but she was out of town and said she would have someone fix it, but I don't believe anyone ever came by. I luckily was able to use my phone's internet, but I certainly racked up some extra data charges $$. I hate to be bound by an internet connection, but having internet access is so critical for modern traveling, especially in cities.