This apartment is great! It's located to the north in Gracia, but a metro stop is less than a block away, so all of Barcelona is still easily accessible.
The apartment is spacious, and has many amenities. You could cook all your meals here (but then you'd miss out on the great food in Barcelona). The hosts also left small packets of supplies so that you'd be able to prepare something small without having to restock a pantry to cook.
The apartment has an American-style coffee machine, so we had a small problem getting coffee filters. You can find them at a grocery store, but you have to ask someone for them - they're usually hidden away since no one uses these kinds of coffee machines in Barcelona.
There is lots of great food within walking distance in Gracia. We ended up going to a nearby empanada place to get food for breakfast each morning.
The apartment is near a school, so if you sleep in, you might be woken up by the children playing at recess. If you are adjusted to the time zone, it's not an issue.
The hosts were really responsive (both over the phone and on WhatsApp, but it was easier for me to type than it is to speak over the phone).
All in all, I would wholeheartedly recommend this apartment. There's a lot of room, it's in a great area, and there are a lot of things within walking distance. Get a 10-ticket metro pass and explore. Or just walk around the environment and enjoy the Gracia. Either way, you'll love your stay here.