This place is great value!!!
I particularly recommend it for younger or budget conscious travelers or if you are just in town for a couple of days and need a place to base your trip out of (which was my case). Penelope was 100% responsive to any inquires I had.
It's best attribute is its right in the heart of Condessa. The room has all the necessities including lots of closet space and decent hot water pressure (which is not a given in CDMX). At the time of my stay, it was definitely the best price for an entire studio apartment.
That said, with such value if you are expecting the quaint charms of higher priced AIRBNB's you may be disappointed. The WiFi was spotty, lighting is basic and the rooms can be loud because all the sound from the internal staircase is heard clearly from inside the room. This isn't anyones fault, its just how the building is constructed (and by no means is it unique to this building, other places I have stayed in CDMX have similar sound insulation issues). Penelope has gone out of her way to post quiet times for the building...but if you are a light sleeper this may be a consideration.
All in all, if you're in town to enjoy Mexico City for the million things it has to offer and not looking to spend an excessive time in your room, this place is perfect.