We (5 students) stayed at Pilar's flat for one week this july and we really enjoyed it. Pilar and her son welcomed us warmly and even gave us kind advices on the city of Barcelona.
The flat was as described : all new, very comfortable and convenient. Even if it's not located in the very center of Barcelona, the buses and the subways can easily bring everywhere.
Don't miss the bus 116 to go from the subway to the flat the first day because the way up to it is very hard with the luggage.
To conclude with, we spent a really good time in Barcelona and at Pilar's place, I lwould come back with pleasure. :)