This flat is very central, 10 minutes walk from Placa Catalunya and 5 minutes walk from the Bus Turistic red and blue route stops, a very convenient location tn explore the city.
We could not hear any street noise despite it being located on a busy street because the windows face an inner courtyard. Both the bed and the pull-out sofa were comfortable to sleep on and there is ample storage space in the wardrobe. The bathroom is basic and quite chilly in winter but it was perfectly adequate for our needs during a short stay.
This flat is run by a team of people which is very helpful because there's someone on-call within the building 24 hours a day. We could leave our bags inside after check-out and come back later when we needed it. We had a great stay and would happily visit again.
One general warning: watch out walking from Placa Catalunya (where the airport bus stops) to the flat. I was pickpocketed within 2 minutes of getting off the bus. Apparently there are a lot of pickpockets in Barcelona and someone burdened with suitcases and distracted with finding their way is an easy target. Nothing to do with the flat hosts, obviously, but something I wish I knew about the area before getting to Barceona so that I would be more careful of my posessions.