The apartment of Esther and Gemma is located very conveniently, 1 minute from a metro station and within walking distance from Sagrada Familia. (Which by the way is worth the money for a visit to the inside. The afternoon illumination inside is awesome.)
We found everything in the apartment is exactly as decribed. It is a bit noisy (streets, metro, bakery) - but then this is probably true for all similar places in the city of Barcelona with its narrow streets. Thus, this is acceptable for a city trip of a couple of days.
Esther was very friendly, could all the time be contacted via WhatsApp and gave us a lot of good recommendations what to visit and where to dine.