This flat cannot be in a better location, just in the middle of Casco Viejo, with all kinds of public transport nearby (tube, "cercanías", tram). Plenty of bars and restaurants nearby as well. However, since there are none (that close late) on the same street, we found it quiet at night, good to sleep.
The flat itself is huge, with plenty of rooms, plenty of comfortable beds and very nice kitchen and living room. We found it very clean and very well maintained.
We really recommend this place for groups or families.