We were a group of 7 and we stayed 7 nights in the flat.
Everything was very cozy, the bathroom is very nice and the bedrooms too. Fully equiped (dishwater, washing machine, dryer). Perfect for groups up to 6-7 people. The flat location was very convenient: next to two subway stations, which lead you directly to the city center, so it was very easy to get to the historic center, the nightclubs or the beach (no need for connection), and right next to the sagrada familia with nice coffees or restaurants. Juan was very friendly and welcoming, he explained us what to visit during our stay and was very available if wa had questions.
However, the rooms are less spacious and darker than the photos lead you to think. We missed dishes (bowl and glasses), and the dishwasher was too small (sometimes had to washing up by ourselves). We can hear a little bit the neighbours but it is not that annoying.
We had a very great stay, and I would recommend you to book Juan's flat if you are looking for a calm district by night, but not so far from the city center and nightclubs.