There's a reason all of the reviews rave about Mercedes and her Airbnb. Mercedes is the best host I've had - extremely communicative before and during our stay. She provided us with a driver to and from the airport at a price that was much cheaper than taxis at the airport. Upon arrival she made us felt right at home and provided us with some cold water and some delicious wine! She gave us some suggestions on where to explore as well as good walking routes around the city and some restaurant suggestions. She also left out some breakfast for us the next morning!
As for the Airbnb itself, it is a bit of an older building but we had no issues at all and enjoyed our 1 night stay. The location is incredible, overlooking a square right next to La Rambla. There is an accessible rooftop area from the Airbnb where you can look down at the lively square. We enjoyed sipping on wine and people watching from up there.
Even though we only stayed one night for a layover, our stay with Mercedes was extremely pleasant and I would recommend this Airbnb to anyone!