My family and I just spent the Christmas holiday at Carlos' apartment. We had a wonderful time in the city and were very happy with our accommodations. Although it is true that apartments and houses in Mexico City can get frigid in the wintertime, we didn't find his apartment to be that cold. It might be because his apartment building is newer and thus better insulated. The apartment has nice big windows that let the sunshine in, so that helps as well. Carlos supplied us with additional blankets; I would suggest visitor's bring thermal underwear or at the very least, slippers for the bathroom floors. The apartment was clean and spacious, in particular the living and dining room area. There is a supermarket literally steps outside of the apartment which is super practical. And a little shop for snacks as well. The building has 24 hours security to allow you access to the building and the neighborhood is super, super safe. The apartment comes with several TV's with access to a bunch of different streaming services. We watched The Marvelous Mrs. Maisel and Roma. Sidenote; the house featured in the film Roma is about a 10 minute walk South.
The apartment is within walking distance to Parque Mexico and Parque Espana, which I absolutely recommend for leisurely walks. It is also near Panaderia Rosetta, the absolutely best French bakery in the city. For the foodies, the Mercado Roma is about 10 minutes away, where you'll find charcuterie, paella, beer and many other food options.
All in all, I would definitely recommend Carlos' place for anybody visiting the city. We never saw him but he was very attentive throughout our entire stay. I would consider returning on future visits.