10/10 location, quiet but central; in various directions it's ~25 mins walk to reach the Gothic Quarter, El Raval, La Barceloneta, La Sagrada Familia, etc. Walk ~2 minutes east/north and you'll also find a surprising amount of very nice quieter restaurants if you're burnt out on all the busy main street tapas places down west. There's a convenient tapas place literally next door where we waited with our luggage for check-in time, and a supermarket and smaller market (open late) and pharmacist all within 60 seconds' walk. Same for metro station and bus station.
Apartment itself is nice; sizeable common area, good aircon, has a little balcony, washing machine (drying cycle didn't seem to work, but clothes dried quickly draped over chairs), bathroom relatively spacious and had a hairdryer in the drawer which was a nice touch. Plenty of stuff in the kitchen too.
Host communicates clearly and responds very quickly.
Other notes / some minor negatives:
*Shower/taps/toilet cause quite a noisy pump to run intermittently, but that's just a feature of old buildings, it wasn't noisy enough to wake any of us up at night
*Freezer was iced up enough that it actually wouldn't totally close, but we told the host and it's probably fixed already
*Mattresses/beds are the usual fare for AirBnb apartments, not as comfortable as a typical cheap hotel but still serviceable (plenty of spare sheets etc also)
*We had to buy toilet paper ~3 days in to a 7 day stay, also had to buy a bucket of pods for the washing machine
*Door access system was a little unreliable at times and slightly confusing for check-in. Apartment access is always via a URL on your phone (save the link as a home screen icon if you can) for an electronic lock, building street access is a URL on day 1 however it deactivates I think at midnight and after that you need to use physical keys (3 copies), which are in a box on a shelf in the apartment. So getting into the apartment requires a combination of a physical key + a working smartphone; if your group is small or splits up, take good care of your phones and their batteries!
Despite those small negatives, still 100% a 5 star review, I feel very lucky to have booked this particular location for my stay in Barcelona.