Pol & Alvaro are really good hosts.
They are kind, available, they answer quickly if you have any question and they can make adjustements if you have special needs, like your time of arrival, etc...
The AirBnb is very clean, well equipped and has a good localisation, 10/15 minutes on foot to the Sagrada Familia.
But what we didn't know was that the walls are very thin and the insonorisation is bad. Your neighbors aren't just your neigbours as you hear everything they do, especially those right over your head. If someone is going down the stairs, you will hear it. Someone walking, you will hear it. A chair moving two floors ahead? Same thing.
We had an especially bad experience the first day with someone putting his/her music very loud (the walls were shaking) at 7:30 am until 9:30 am. The music was followed with massive footsteps. We asked our host if they could do something and they were very comprehensive of the situation and the music stopped. Anyway, there were some public works outside and some cleaning in the building. Resting was quite difficult.
The hosts couldn't do much about the noises and tried to help us as much as they could. This AirBnb might be the perfect choice if you are planning to visit the city starting early in the morning but if you are a nocturnal bird, maybe you won't be able to rest as much as you would.
Even if it was bad luck with the music and the public works, the insonorisation is bad.
But again, Pol & Alvaro were good hosts as they tried to make our trip as enjoyable as they could.