I was staying for one month at Benjamin's apartment right in the city center. Benjamin is a really nice host and communication before and during the stay was really good and he provided prompt help.
The apartment itself is really nice with a great view from the 22nd floor. I would totally recommend it for a short visit to Santiago - but for a long term stay, I would suggest some other areas. The only down side for me was that kitchen utensils were a bit battered.