We had a great stay at Evelin and Gisele's. The apartment was just as depicted and very comfortable for our family of four. (I think it could be tough for six, with one small bathroom, unless people were on quite different schedules.) The neighborhood is great -- markets, restaurants and stores just steps from the front door.
Our first night was pretty hot, as Barcelona was experiencing unseasonably warm weather, but other evenings we cooled the apartment down nicely by opening the shutters when we returned home after our adventures.
Parc Guëll is a nice walk away and La Panxa del Bisbe, on the way home, was fabulous for dinner. Fabulous.