Diana is an awesome host because she is very attentive and responds quickly. We are a family of four and there was enough space for us to be comfortable in the apartment. It was great to have the flexibility of cooking something for breakfast/dinner, and washing our clothes. In the summer, it is no mystery that Barcelona gets very hot, and an A/C unit in the apartment works but does not do a lot to keep the apartment cool. After talking to Diana she brought over a standing fan for us to use for the end of our stay which did help.
The location of the apartment is fantastic if you want to experience what's it's like to be more of a local. By the bus that picks up right outside the apartment, Plaza Espanya is only around 10 minutes away, and with another bus that picks up very close by, you can be at the metro in about 3 minutes. Otherwise, the metro L3 line is a 10 minute walk away. With these modes of transportation it is relatively easy to see the city and travel anywhere.
There is a grocery store only a 5 minute walk away that is open late, and a bakery and fruit store down the street from the apartment building that I highly recommend going to. There are two restaurant/bars on either side of the apartment entrance, I would not recommend eating a full meal there, but it's a great spot for a drink and some tapas after walking around all day.
All in all, we were very pleased with our stay in Barcelona at Diana's place, just keep in mind when visiting in the summer it could get very warm.