I stayed in Sergio's apartment for a month and found it to be a very comfortable place to stay. The kitchen was well equipped, and there was a water filter next to the sink. There's a living area, dining room table, and a modern TV to watch Netflix. There's an HDMI cable for your own Apple TV or laptop.
There's tons of closet space with plenty of drawers and hangers for all my clothes. The bed is a little on the firm side but comfortable. This apartment has no A/C like many in Mexico City, so having a portable fan was essential for my comfort.
There's a massive patio with lovely tower views along Reforma and plants, which I watered during my stay. Sitting outside was beautiful, and feeling the breeze when the temperatures dropped.
The second bedroom is a small annex encased with glass and accessible from the patio. It had a desk, bed, and bathroom. I seldomly used the space and found myself using the dining room table as my desk when I worked from home. The Internet connectivity was very fast, getting up to 250 MB down.
The building is secure, and the building manager was super friendly. Silvia provided keys and instructions when she met me when I arrived.
The location is fantastic in Col. Cuauhctemoc and is within walking distance to Rio Lorma, where there are many great restaurants. It's walking distance to Reforma, a beautiful boulevard where much of Mexico City meets. I found it very safe to walk at night as the streets are well lit, and the neighborhood is primarily residential. On Sundays, they close off Reforma so bikers and pedestrians can use it, and I ran along Reforma every Sunday. You're also within walking distance to Chapultapec Park. Zona Rosa is 15 minutes, and Condessa and Roma Norte are about 30 minutes walking distance.
Overall, a nice place to stay.