Very cosy little apartment with lots of day light thanks to the big windows, and very comfortable bed. It is downtown so be prepared for noise if you sleep with open windows. What other guest have wrote about the lock is true you have a common doorknob push lock like you normally have on a bathroom door, but there is a guard at the building entrance, that registers every person that comes and goes, we never felt unsafe. As for the area you are in the the historic center of Mexico city probably one of the more guarded neighborhoods no problems there, but of course like in any big city you should always keep your eyes open.
The walls are quite thin between apartments you can here the neighbors on both sides. Beautiful rooftop although during pandemic times only the open part is open. All in all nice small place to stay for a few days. Would do it again.