This is my third AirBNB in three years in Barcelona and it was definitely the best.
The street outside is pedestrianized, lively during the day and filled with locals, and with good eating and drinking options day and night.
Public transport is 2 minutes walk away.
The apartment itself is great - spacious, clean, modern and with 3 aircon units (and with the weather in Spain at the moment you would need them). All mod-cons (kitchen, tv, wifi, washing machine) present and in good order.
The bedroom is to the back of the apartment and was lovely and quiet.
The only negative is that there are a lot of stairs to get to the apartment - but that didn't bother me much and it was the same story at every other AirBNB I used in BCN.
All in - this was a great AirBNB - it would be perfect for singles, couples and families and looks very well set up for a small group too.