I stayed there for about 10 days. They responded my texts pretty quickly and it was very helpful that they speak English.
Pros:
It's walk distance to: metro, restaurants, pharmacies, Lastrarria neighborhood, grocery store (bellow the apartment building); The location is right at the center of Santiago. It's about 20 minutes walk from the Parque Metropolitano de Santiago/ Cerro San Cristobal.
Apartment looks like in the pictures;
The smart lock keypad door lock was handy;
Internet worked ok;
Bedsheets and towels were clean;
It has pretty much all utensils needed for a comfortable stay: hairdryer, fan, pans and kitchen utensils, coffee machine, toaster, iron, wash and dryer in unit, etc.

Cons:
They did not left toilet paper and basic cleaning products such as paper towel, trash bags and all purpose cleaning;
The apartment was full of cockroaches;
Kitchen and kitchen supplies were a little dirty;
There was a lot of noise during night time every night (until about midnight-1am)
If the curtains were open you could see and be seeing by many neighbors.