The apartment is in a central location walkable to the Plaza de Armas, central market and Cerro Santa Lucia. I actually also walked to Cerro san Cristobal with a lot of stops in between. It's also just two blocks from the metro. During peak hour, the traffic around that area can be terrible due to the number of one-way streets so do stick to the metro or walking.
Very secure building with a laundromat on the first floor costing 1300clp each to wash and dry (do bring your own detergent as it's not provided)
Apartment is clean although you'll need shoes or slippers to walk around and the light in the toilet is a bit dim especially around the bathtub. But apart from that, it has a well equipped altho small kitchenette attached too, ideal for light cooking or to heat up simple stuff.
All in all a great location to spend a few days in Santiago.