The studio was almost perfect : modern, really clean, comfortable and with great equipment (towels, iron, immersion blender). I didn't meet Patricia and Rui (out of town) but their friend Carla who was very nice and efficient : she kept my bags for me when needed. She also gave very clear information about everything you need to be comfortable in the flat and the area, and if you need advice on restaurants, places to visit, shopping, etc... her knowledge can come very handy! The communication was super easy.
Plus the location is pretty central. There are also 2 metro stations near by but I walked almost everywhere.
The only downside to the apartment is the isolation : the neighborhood is pretty alive at night during the summer and the street noise gets to the studio. I also had noisy neighbors : a group of 5-6 people on vacation and the isolation of the building is not good enough to cover that. It's a shame because it's something that's pretty difficult to handle, but it needs to be pointed out for people whose sleep depends on absolute silence.