We had such a lovely time at Rafael's apartment.
Rafael was a great host, organising an airport transfer (including car seats for the kids) to meet us at the airport at the end of our extremely long journey from the southern hemisphere.
There was plenty of room for 6 of us (two kids, two parents, two grandparents), and Gracia was the perfect location. Just a bit out of the main tourist area - which meant it was a breeze to find 6 seats at whichever neighbourhood plaza restaurant we fancied - but not so far that we felt removed. Actually, it was the perfect location to walk to Sagrada Familia, and Park Guell. (We caught a bus up the hill to the Park, but accidentally walked home afterwards, just ambling back down for lunch.)
Joanic station is literally moments from the door, making it very easy to head in to the Gothic Quarter, the beach, etc.
There are plenty of bread shops, supermarkets, bottle shops, cafes, restaurants, etc. around, so no shortage of options for eating out or in. The kitchen is reasonably well equipped. A decent knife would have make cooking easier on the nights that we stayed in, but that's a pretty standard airbnb quibble.
We never ran out of hot water, although did have to stagger showers, as more than one water source going at once meant the bathroom water was momentarily cold. Not a problem once we figured out what was going on.
The washing machine was a godsend, especially with two kids.
There was a little bit of street noise audible in the front bedroom at night, but nothing that earplugs couldn't take care of. The kids and grandmothers slept completely soundly in the rooms at the other end of the corridor.
All in all, a really fantastic place to stay. We would absolutely recommend the apartment, and Rafael as a host.