Overall Impression:
If I were in Barcelona with a group of friends for 3 days and were looking for somewhere to stay, this apartment is your place. If you are looking to stay with only one other person for a vacation, I would recommend a location closer to the beach that provides better amenities for the bathroom (i.e more towels, better shower) and better internet connectivity.
Positives:
very easy check in with keycode to enter, semi-central location but not for younger crowd. Great bed in Master, but twins in rest of apartment. Close to Pharmacy and metro stop.
Negatives:
The Apartment is made for a group of people and not a couple should be noted. I have stayed in AirBNBs across Europe and was surprised that for a five day stay we were only given two bath towels, no electronic converters, and that the Wifi only worked half of the time. The apartment only provides the basics. Neighbors were noisy above us at night but not unexpected.
Location: 10 min walk from La Sangrada Familia, you are about a 30-40 min walk from the beach, Las Ramblas, Gothic Quarter, and El Borne so plan accordingly for cabs and the metro.