Angel was a good host and answered his Whatsapp and Airbnb messages quickly. He booked us a taxi back to the airport and the check-in with his friend went very smoothly. It's worth noting that you will have to pay a residency tax (I think this is what it's called) when you arrive, which was something like 4 euros per person per night- so make sure you have cash. This is a standard in Barcelona, I believe, not specific to this listing, just a good thing to note.
The apartment has the amenities you'll need, including towels, linens, hair dryer, ironing board, and kitchen equipment. It's quite nicely decorated and is a great location for La Sagrada Familia (which you can glimpse from the terrace) and walkable to many other locations.
While it's generally a nice apartment, it is not quite as lovely as it looks in the images. The terrace is not properly covered so lots of apartments look down onto the terrace. There are some odd design issues with the layout of the flat, and we found we couldn't use the upstairs en-suite shower as water came running down the kitchen wall if we did- we then noticed the shower floor upstairs seems to be wood. This meant 5 of us sharing one bathroom/shower, which was fine, but may not be ideal depending on your circumstances.
It is also worth noting that the upstairs double bedroom is not exactly private- you can clearly hear everything going on in the kitchen and living area, and vice versa, as it's basically a mezzanine and not closed off. I found that as soon as our friends were out of bed in the morning, even when whispering, it was like they were standing next to us and woke us up. So do not expect privacy from this room.
Lastly, the lack of soundproofing on the apartment overall, as mentioned in other comments, is quite a problem. One of our friends sleeping in the front bedroom overlooking the road could not sleep without earplugs, and the friend in the middle bedroom said there was a baby upstairs who cried through the night which woke her as it carried through the vents. If you are heavy sleepers and do not need too much privacy this flat is fine, but otherwise I would not recommend it.
Overall it was not an entirely negative experience and we did enjoy sitting on the terrace in the evenings and were generally comfortable, but I expected slightly more from the flat than it offered.