My family (myself, wife, and three elementary school aged daughters) rented this apartment for our 4 day visit to Barcelona. The communication leading up to our stay was excellent and I got a response within 5 minutes when I had a minor issue that I needed help with. Overall, the building and apartment were very nice. The entrance to the building is controlled by a key fob, and was very easy to get in and out of. The foyer is well kept and there is a small elevator to take you to upper floors. The unit is pretty much on par with the pictures, which is to say very nice. It's bright and clean and has nice high ceilings and big windows, which make it feel very spacious. The kitchen and two bathrooms are well appointed and fairly recently renovated. The only negatives I would make would be in regards to the plumbing. The master bathroom has a pump that makes an awfully loud sound when you draw water (i.e. flush, run the sink, take a shower). Not really a big issue, but I wouldn't flush the toilet in the middle of the night, or you could risk waking someone. Also, the hot water doesn't come in a steady stream, so when you're taking a shower the water will go from cold, to scalding, back to cold every 30 or so seconds. It's actually not as bad as it sounds, and you adapt pretty quickly, but definitely not ideal (and you have the pump in the background making noise to boot!). Perhaps this is normal in older buildings or units with on demand hot water, but I certainly wasn't prepared for it.
Overall though, the unit is very nice and I'd recommend it.