Our stay was fantastic. Place was clean, has everything you needed for the stay, and best of all had a beautiful view of Sagrada Familia. It is located a few steps to la Sagrada, with a lot of choices to eat from around the place and a supermarket right next to the building. It had metro just down the block, and taxis all around. The park infront has a play area for kids if its something you need.
Two things to keep in mind. First, which has nothing to do with the stay and/or the host. Places in Barcelona, and also in general in Spain, they tend to close early and Sundays a lot of places closed. Just make sure to plan ahead if you need to buy things, specially supermarkets. Restaurants most of them do stay past 10pm.
The other thing is the airbnb is in a 5th floor, and we encountered a few times issues that elevator does not work. Its very old and some of the others living in building said that it has a lot of issues and they cant really do much to fix. So lots of stairs to go up/down if not working.
Other than that, this place is a really nice location to stay at, centric, and the host is very welcoming with lots of information to provide. Cant think of anything negative of the location, other than a fun stay to be able to visit all Barcelona.