We had a perfect three-week stay here! (Family of four with two teenage boys.)
The apartment: clean, very quiet at night, strong WiFi and well-stocked with towels, fruit and drinks upon arrival. The kitchen had everything for cooking a simple meal. There is a 24-hour security guard who lets you in the main entrance and can answer questions about the neighborhood or building. The apartment is on the 4th floor with no elevator. Shower has good water pressure and hot enough water.
The neighborhood: We wanted to stay in a non-touristy place and Sta. Maria La Ribera was amazing for this. We also felt very safe walking around, even at 3 a.m. in the morning. On our block we had two bakeries, multiple restaurants with meals for $3 US, a great sandwich (torta) stand, several coffee shops and a very popular churro and crepe shop. The laundry on the block did a great job washing, drying and folding our clothes. We were two blocks from the Kiosko Morisco - a plaza with an ornate gazebo and always lots of activity. Great for people watching and snacking on fruit, ice cream, elote (corn), etc. The neighborhood does shut down around 10 p.m. So if you are interested in nightlife, you will need to take an Uber to find the activity. (We did this multiple times.)
Nearby: Also within walking distance is a Thursday street market and a Saturday market called Tianguis el Chopo that is worth checking out. Lots of alternative music and clothes. My favorite destination was the local library -- Biblioteca Vasconcelos -- which is an architectural marvel surrounded by serene gardens.
Transportation: We used the metro (subway) almost daily. It is a ten minute walk to two different stations (depending on which line you need), and then about 15 minutes to the Historic Center. It was also ten minutes walking to the red Metro Bus station, which was also easy to use. We also used Uber regularly and paid about $2.50 - $5 US for most rides.
The host: Clemente was always quick to respond to our questions and helped us with any concern.
If you are looking for a safe, comfortable apartment where you can experience daily life in Mexico City, this is your place!