Our stay at Matias's place was just great. The location is perfect if you want to explore the city on foot. Every single tourist attraction is within 10-15 min walk and all the bus stops are on the main square.
Matias welcomed us and let us leave our baggage before the official check in, which was really convenient.
The only thing I could mention as not so good is the shared bathroom. It is somehow awkwardly organized, too small, but even though it was cleaned on a daily basis.
I would truly recommend Matias's place, primarily because of the location and because of the good communication with the host.