Alex's apartment is great. It's in a quiet location, off the main area but it close enough where it's easily walkable. The building felt very secure and was comfortable. It's located on a street so you do get a little street noise but there is a fan that can be turned on to provide background noise. My wife is a light sleeper and the fan was perfect for covering any noises from below. Alex also provided a comforter for the bed which was great as it was colder at night than we were expecting. Also, the layout of the apartment is perfect as the bedroom and kitchen are separated. If one of us woke up first, we could go about our morning without waking the other. The washing machine was great and much appreciated as we didn't have to track down somewhere to wash our clothes before leaving Mexico City.
I'd highly recommend the apartment and location. As I said, we walked pretty much everywhere -- all over Roma Norte, Sur, La Condesa, Centro. If walking isn't your thing Uber is a quick and easy option. We did this to Centro one day and it was a quick ride. Finally, we really appreciated the easy (WhatsApp) communication. Although we didn't use it much it was nice to know we had a quick and easy method to communicate, if necessary.