The apartment was located in a pleasant and convenient spot, close to amenities, handy for the Urgell or Universitat metro stations (and about a 15 minute walk from Paseig de Gracia station, where we got off the train from the airport). Many of the important bits of the city are within reasonable walking distance (but due to the proximity of the metro stations, you don't have to walk).
We were given good advice about what to see around the city. Only having a couple of days we were a bit limited in scope, and even though it was February we still didn't manage to get into places such as La Sagrada Familia because tickets/suitable time slots were sold out. It seems that booking the day before is not soon enough. Be organized and book early.
One recommendation we were particularly grateful for was La Flauta - a nearby tapas restaurant. Excellent food and reasonable prices - highly recommended.
Overall the standard of accommodation was good, although there are one or two features that might repay attention. The shower head in one of the shower cubicles was broken & spraying water everywhere - still usable, but I'm not sure for how long. The other shower cubicle was rather poorly designed and water flooded everywhere. The downstairs neighbours might become unhappy.
The only real downside of the apartment was the lack of utensils. We found no scissors, only one sharp(ish) knife, and no proper glasses for wine or (gasp!) Cava. We didn't try cooking anything but would probably have had a tough time if we had because of the sparseness of the kitchen.
But a good experience overall.