Sandro's apartment is quiet, spacious, and well located in the Gracia neighborhood, and Sandro is a friendly host. The first floor is especially nice; as others have noted, the lower floors are a bit musty, the stairs leading down are steep, and the wifi only works on the top floor.
Although we enjoyed our stay overall, we did have a couple of problems related to the apartment. First, we were unable to use one of the two bathrooms and the washing machine for two of the five days of our visit because of plumbing problems. This was a significant inconvenience for us, since my wife and I were traveling with our parents and it was important for us to have the use of both bathrooms (we had also planned to do laundry). Communication about the plumbing problem with Sandro and his sister, who lives next door, was also difficult--at times they were telling us different things. Although I understand that the problem has now been fixed and is unlikely to happen again anytime soon, it detracted from our stay. The second problem involved the locks on the inner and outer doors, which must be fully engaged from the inside in order to be opened from the outside. Sandro explained the locks on the inner door, but he did not make clear that both locks worked in the same way. My wife and I were locked out of the apartment on our first night as a result, and we were unable to wake the others inside the apartment because the doorbell had been disconnected.