The appartment was really nice and we enjoyed our stay there. It was mostly clean and everything you need was nearby. (Shop, restaurant, metro etc.)
The only two negative points were the kitchenware and the sounds early in the morning and late in the evening. The kitchenware was just disgusting. Most of the pans had a black, sticky layer on the bottom, which looked like food residues of the last time they had been used.
The were a lot of sounds in the neighbourhood (like talking across the street, opening windows, flushing toilets), which can be really annoying if you want to have a good night of sleep. We didn't mind at all and slept through it all, but it is something to take in to account.
I may have summed up more nagative points than positive points, but we really do recommend staying here. If I were to go to Barcelona again, I definitely would consider staying here again. All in all we had a very nice stay.