This is a great apartment for exploring Barcelona. The bed was comfortable (I rarely say that about European beds), the kitchen was well-equipped, and it was great to have a washer/dryer. The location is fantastic. The Sagrada Familia is right around the corner. The metro station (serving 2 lines that make all of Barcelona easy to get to) is maybe a 2 minute walk away. There are dozens of great little restaurants and cafés in the area.
The host is wonderful. Laura is a fantastic communicator. She met me at check-in to show me all the features of the apartment. She was easy to reach if we had questions, and was extremely helpful with restaurant and neighbourhood recommendations. She has a great pdf guide (also in written format inside the apartment) that she includes with the booking, and it is a wonderful starting point for exploring Barcelona.
The negative consequence of staying in a convenient, busy area is the street noise. Be prepared for it. We packed earplugs for sleeping, and we were very glad to have them. It is fairly quiet between midnight and 0700, but outside of that, it is a busy neighbourhood, and you will notice the road noise (nothing to be done other than to prepare yourself).
That said, we give the host and the apartment a whole-hearted 5*'s. We look forward to staying here again and to recommending it to our friends and family.