The flat is very nice, very well located, close to bars and reataurants but in a quiet area. it has everything you need for your stay, including a fully equipped kitchen to cook something yourself and a washing machine, very handy if you're travelling for a while.
There is also a small balcony overlooking Santiago, very nice.
The building is safe and there is a concierge at the reception.
Communication was smooth and we had no problem with the check-in process, despite arriving fairly late in Santiago.
The only small issues we found was with the water pressure in the shower, which was not great and the sink in the bathroom, which was slow to drain.