We stayed here in a group of 6 for one week and it was a brilliant stay. The apartment is lovely and really big, the photos don't really show it but we were pleasantly surprised when we arrived.
The beds were comfortable and the kitchen was well stocked with pans & plates etc. We only had two keys which was a pain sometimes as we were a large group but we worked it out between us. It is in a great area, close to the Diagonal which is a great place to get a taxi (super cheap in Barcelona, we used them often). About a 25 min walk to some sites like Casa Batlló and La Sagrada Familia.
There is a fantastic restaurant just outside the apartment called Bar El Velódromo that we went to on our last night. Totally recommend it!