I spent three weeks at Carlos' place, and it has been very nice.
The location is quite good, in barrio Italia, and not far from the Irarrazaval subway station. For such a long stay as mine, it would have been nice to have a washing machine in the building (but Carlos had clearly told that there was no washing machine available so it is totally fine). Otherwise the studio has everything one can expect, it looks very new, it was perfectly clean, the wifi and heat were functional, and I liked the view on Santiago.
I would clearly recommend it (or come back).