The apartment is clean and cozy, and the location is a 5 or 10 minute walk to Sants station, which could be convenient if you have a short transfer stay. The neighbourhood is central and safe, though not super exiting, so if you plan your BCN trip well in advance I would pick a flat in other areas like El Born or Gracia. But for a last-minute booking (like in our case) this place may be of better value, due to the high tarifs all around BCN.
The downside for me were the supplementary costs to be handed in cash on arrival. It should be part of the AirBnB total price. Same for the regulations of early/late/weekend check-in / tourist tax. So make sure you read the rules properly before you hit the "instant book" button. It feels like it's only about getting the money, and it took away the charm of the apartment for me.
Sylvia, the lady handling our check-in and checkout was very friendly though.
Overall value, I found it too expensive.