The apartment was really great. Spacious and really clean. The location is ideal, you can reach the center on foot or with public transport easily. Plus the connection with sites that are further away (e.g. park güell, camp nou) is really good. The only negative comments is the sewer-like smell that comes out of the bathrooms at some times during the day and the soundproofing which is almost non-existent (minor problem because it is quite quiet in the area).
Overall great experience, I would definitely stay again there! :)