We (2 + 2 children) had a wonderful 5 week stay in Barcelona. Rafael and Tania were very nice hosts, always quick with their replies, accomodated all our requests and provided some good tips for living in the city of Barcelona.
The Apartment is large, light, cozy and overall: perfectly located! The Metro station Joanic is literally 30 seconds away, if you need to get somewhere quickly (15 mins to the Beachfront). Sagrada Familia is a 12 minute walk and so are Park Güell and Passeig de Gracia.
The Gracia neigbourhood was great: Not overrun by tourists, nice places, small cafes and bars, some boutiques, ... some sort of festival every other weekend, where mainly the locals gathered...
We enjoyed it very much and would happily stay there again.