Pros: strong air conditioning during a heat wave; clean apartment ; responsive rental company/host. The apartment is very much as it looks in the photos, with Ikea furnishings.
Cons: the apartment is not in the heart of Gracia. It's in a nondescript residential neighborhood with not much going on, about a 15-20 minute walk to get to the cafes/restaurants etc. of Gracia. It's about a 15 minute walk to Sagrada Familia; about a 6 minute walk to the Joanic metro.
Also, we were a little cramped with 3 adults; the bathroom is tiny. There is a pullout couch, but I wouldn't recommend this for 5 people, as it's advertised.
The street itself is quiet, though while we were there they were doing construction in the adjoining building, so there was some building noise during the day.