We loved our trip to Barcelona the apartment is great - just as described. There was quite a lot of building work in the street outside but this didn't bother us. The windows are all modern and double glazed.
The beds were comfy and the apartment had all the towels and pillows sheets and blankets you could ever wish for.
The apartment is on the third floor which was fine. There is a lift but it's slightly antiquated so we ran up the stairs with the kids and really only used it when we're carrying luggage up or down.