This was my first Airbnb experience, and it was excellent! And I have elite status in a few different hotels chains...but this experience may change my booking habits in the future.
First, we arrived earlier than expected, and Rebeca still met us at 9:30 a.m. This meant we had the full day to enjoy Barcelona.
The apartment is excellent -- as described. I know some people said it can be a little loud downstairs, but this is nothing more than the sounds of living in a major city. But you can't beat the location. I have visited Barcelona many times, and actually stayed at a hotel a block away from this apartment. This area is my favorite, since you can walk to the El Borne district (best restaurants!) and Barceloneta.
Bottom line: you can't go wrong here. When I travel, I look for a place where I can sleep, since I spend more time exploring/enjoying a city. This apartment on Airbnb enabled me to do just that.