All in all, we had a great stay in Barcelona. The apartment is clean and nicely equipped.
One minus point was the checkin which was not possible via the porter as described on Airbnb. Instead, there was another person which we thought was a random inhabitant of the house because her English wasn't that good. Long story short, after waiting and calling the hosts we finally checked in 45mins after actually arriving.
Nevertheless we would recommend that apartment and had some nice days in Barcelona.