My wife and I stayed at Mercedes' place for two weeks and had a pleasant stay. The apartment is in a great location within walking distance from restaurants, supermarkets, malls, and other types of shopping, as well as several tourist attractions, such as Recoleta Cemetery. It's also only a couple of blocks away from two subway lines. Just be aware that the subway closes early, but you should have no problem getting an Uber back to the apartment.
The apartment seemed fairly new and is a bit small, but still comfortable. The kitchen had everything needed to prepare meals. There is a private washing machine outside and a clothes line to dry your clothes. The shower was nice and hot with good water pressure. The TV, located in the bedroom, has Netflix and a Chromecast. The wifi was very fast and reliable and there was a nice table for us to work at.
Mercedes was very responsive and helped us with any questions or issues we had. The biggest issue we had was that the water heater stopped working but she quickly got it fixed.
Other issues we had with the place unfortunately cannot be fixed. The apartment, which is on the first floor, doesn't have access to much natural light. There are windows in the bedroom and kitchen and a sliding glass door in the living room, but they all look out to the patio, which is basically a small courtyard surrounded by several floors of other apartments and the only light that comes in is from the top of the building. Some nights when we went out, we just assumed it was dark out but were surprised to see it was still light out. The lack of light and any sort of airflow also made it a bit hard to dry our clothes. And I was nervous about leaving our clothes out for so long because people in the apartments above us ashed their cigarettes and threw their cigarette butts down on the patio.
We didn't have a phone signal inside the apartment so you'll need to go outside on the patio, which still doesn't have a great signal, but it wasn't an issue for us since we make all of our calls over wifi.
Obviously, with this being an apartment building, you shouldn't expect it to be quiet. There was noise all throughout the day and night. So depending on your tolerance level, it might not bother you, but I found it to be very distracting at times.
All in all, it was a really nice place in a good location with a great host, so if the lack of natural light and a weak phone signal won't be an issue for you, then I'd recommend it.