The apartment was large and spacious. I was traveling with two friends, and we had the ability to hang out or chill by ourselves as needed. Antonio was responsive and friendly. When we first arrived, the apartment internet was out due to a copper wiring issues for the first two days of our stay, and he worked to provide a temporary workaround (as we are from the US and our mobile data did not work well at all) until it could be fixed.
The only caveat I would mention is that due to the apartment location next to Parque Bustamante, it can get very loud until very late in the evening. Friday nights especially (and several other nights in the week) it was often loud until 1 - 4AM due to revelry in the park. Just food for thought for folks who may want to stay in a quieter location.
In general, our stay was good, the apartment is a good value and a good location to explore Santiago.