We loved our stay at this apartment. We finished off a 10 day trip to Spain with 3 nights in Barcelona, and I would stay in this apartment again if I ever go back.
-It is in a great location in the Gotic. The street is pretty quiet, considering you are in the middle of Barcelona (I don't think there is really any place that is REALLY quiet in the city!).
-The apartment is an easy walk to just about everything - Las Ramblas, the Parc de la Ciutadella, the Picasso museum, Gaudi sites. We even walked (easily) to Sagrada Familia and to the beach. If you prefer to get around by subway, the Urquinaona stop is a couple blocks away from the apartment.
-The apartment is nicely appointed and very comfortable. My wife and I slept comfortably on the bed in the master, and our 21 year old son (studying in Salamanca) had a room with 2 beds to himself.
-We love to cook (which I why we pick apartment rentals for our trips), and there is a grocery across the street from the apartment. But, the Mercado de la Boqueria is a 15 minute walk from the apartment and is more fun. Even if you don't want to cook, you should go there to stock up on wine, olives, cheese, etc. for snacks.
-Horacio is a great host. He met us on time at the apartment, was very communicative before our stay, and provided us a map with lots of recommendations for restaurants, things to do, etc. This contrasted with some other apartments we have stayed at (including one in Madrid), where we got almost no information about check-in and no personalized attention when we got there. Thanks Horacio!
-The apartment is older, in an old building, in an old city. If you are expecting a pristine modern apartment, then book a room at the Westin or some American chain hotel. Part of the charm of staying some place like this is having the washer/dryer (yes, there is one!) in the atrium (or whatever you call it) outside. We enjoyed the funky aspects of this type of place.