Location, Location ,Location.
The apartment is in a fantastic position , only a few minutes from the Sagrada Familia so you can see it at all times of the day.
Also recommend Hospital Sant Pau which is just up the road and is amazing.
We had a great meal sat at Casa Madre Taberna Moderna . Amazing tapas eaten looking at the Sagrada Familia.
There is a lot of traffic noise in the front bedroom as previously mentioned but Barcelona is a noisy place. I took ear plugs and this helped.