The apartment is brilliant - spacious, light, clean and well-equipped. The bed is comfy, and the air-conditioning was a lifesaver in the heat of summer. The only thing we missed was an electric kettle to boil water for tea (there's a filter coffee machine) - but boiling water in a saucepan on the induction hob was quick and easy too.
The location is not especially central, but the metro station Collblanc is just a few metres from the door and it was really quick and easy to reach all the sights. We also liked being away from the touristy areas - it was quiet at night but still felt perfectly safe.
Communication with Alex and Monica was quick and relatively easy, although the language barrier meant we did rely on Google translate to try to communicate in Spanish. Check-in was very smooth - we didn't meet Alex or Monica, but a lady called Maria was there to give us the keys and point out important info. For check-out, we were asked to simply leave the keys in the flat and shut the door. Alex and Monica were wonderfully flexible about check-in and check-out times, which we really appreciated.
Overall, we had a great stay and would thoroughly recommend the apartment!