Serjio is an amazing host. Very friendly and always available to help in any way he can. He always responds quickly and gave me all the tips on how to get to his apartment. The room is exactly like the one in the ad and the bed is really good. I slept like a baby. There is also a large shopping center close to the apartment which is a good base. The Besos Mar metro station is just a few meters away of the apt.
The downside is that the apartment is far from the center of Barcelona. Approximately 25 to 30 minutes by subway. So basically I became dependent on the subway, which has a high cost. The distance also means you have to stay out of the apartment all day, leaving early and returning late at night.