The best location you can imagine, sandwiched on a relatively quiet street between La Graçia and la Rambla Catalunya. You can walk to everything from here.
María and her colleagues were very responsive and check-in was easy. We paid the 25 euro fee for a late check-in and Carlota met is at the apartment after a short wait. The apartment is cheaply furnished and wasn't super clean, but the space was ample and otherwise comfortable for our family of four.