We had a good stay in Mercedes place. The host was helpful and the location is nice and even closer to the center than we could imagine. The walk to the city center and old town was only 10 minutes which was great.
My mother is sensitive to cold and felt cold inside (we were traveling in February) but luckily there was a extra heater which she could use. For me the room temperature was no problem.
All together the 1 week stay was good and I'd recommend the place to anybody traveling with budget and want to stay close to downtown.