We booked Mata's place for two weeks. There were many amenities necessary for a long-term stay in the apartment. There was only one thing missing from the apartment listed by mistake: a microwave. Due to this mistake, Mata's was very responsive to our concern and agreed to offer a small discount since it was his mistake that he listed it.
This Airbnb is in a quiet, residential neighborhood, but is still very central (super close to many restaurants, public transportation, and minutes away from the Sagrada). Though it was in a quieter area, there were a lot of students living in this complex, and the walls were paper thin (which is common in Barcelona), so you could hear your neighbors across the hall and upstairs. As well as outside. The students who lived in this building were very loud at night and threw many parties until early in the morning. There is also a daycare/school located across from the apartment, so if you sleep on the sofa, you will be woken up by the children playing outside.
The only other complaint I have is that the WiFi wasn't very stable. The internet would occasionally be extremely slow or stop working altogether. If you work from home, this could be frustrating.
We had a good experience overall, despite the few mishaps. The apartment was spacious and very clean, and it was also centrally located yet away from the hustle and bustle of the city. Most of the mishaps we encountered were out of the host's control (such as the neighbors or being close to a school).
I'd say this place is the perfect size for three to four people. As long as you don't mind the noise, or plan on not staying in the Airbnb all day, then I would recommend staying here.