We had a fantastic stay at Javier's apartment, I honestly do not think you will find a better place to stay in Barcelona. The two outstanding features of the apartment is its location and views over Placa d'Espanya.
Located on the L1 & L3 (red and green) metro lines means that you can get to most attractions in Barcelona without having to change lines and the apartment is only 50 metres from the Placa d'Espanya metro which is really handy after a long day of walking.
The views from the terrace are amazing, grab a bottle of wine & watch the sunset. You can also watch the fountain light show in front on the National Museum from the terrace.
The apartment was super clean and Joanna met us there and showed us around. We caught the Aerobus to the apartment from the airport which took about 30 mins - cost EUR 5.90 but you can catch Bus 46 which will drop you off at Placa d'Espany for EUR 1. This will take a lot longer to reach the apartment.
The apartment however is smaller than the photos suggest. It sleeps 5 but you will struggle to fit everyone in the living room - we were 2 adults and 1 teenager so the space was fine.
Lastly make sure to visit Pl. Reial and have the menu of the day for outstanding value and enjoy the ambience of the square!