I stayed with my wife for 4 mights at Lucy's Room and we really liked it. The location is absolutely centrally located. We nearly walked everywhere. the metro as well as the Ramblas are also just a foodstep away.
Lucy's flat is very clean and Lucy herself is a great host. When we arrived she directly offered us something to drink and then showed us our room and the rest of the flat. The room isn't that big, but it worked out perfectly, since you do not want to spend your time in your room, when you are in Barcelona. But we loved sitting on the small balcony for a last drink before we went to bed.
For a good sleep we recommend to bring some ear plugs, since a city like Barcelona is not silent at all, especially since you sleep with an open window, to cool down the room.
For our next trip to Barcelona we would like to come back to Lucy's room.