I stayed at Esther's apartment for a long weekend with my wife and 2 children (3yr & 0yr). The location was fantastic and at the top of Las Ramblas. There were metro stations, the airport bus stop and a 24hr shop all within 5 minutes walk.
The apartment is very quiet and although it's lively out on the street you don't hear any of it. It's actually located on the back side of the building so there is absolutely no noise which was great with the children at night.
The pictures are very accurate, beds are comfy, kitchen has plenty of utensils and the internet was very fast, I really can't fault it!
I would definitely recommend staying. Esther was a great host from point of booking, arrival through to departure.