This place is in the perfect location to see the highlights of Barcelona. It's just across the street from Placa de Catalunya (which is considered to be the city center), and right next to the famous La Rambla street. It's right next to the Gothic Quarter to the southeast. I walked to all of the popular places, including La Rambla, La Boqueria, Placa Reial, the Columbus Monument, The Cathedral, Casa Batllo, Casa Mila (La Pedrera), Sagrada Familia, the Gothic Quarter, Barceloneta Beach, the City Park, and the Barcelona Zoo. The only thing I used the rail for was to see Park Guell, which is a bit further north. The Barcelona City Tour Bus has a stop at Placa de Catalunya. For about 30 Euros, you can get a 2-day ticket, which has 2 routes that hit all the popular tourist locations (all the places I listed above, as well as the 1992 Olympic venues, and stops at some great vantage points where you can take pictures of the city with the Mediterranean Sea in the background). You can get on & off the bus as much as you want. There's a place called City Hall where you can see a Flamenco Show just a few steps from the apartment. And there are great restaurants on the very street where the apartments is. I ate great restaurants every night, never had to walk more than a block or 2, and never had to eat at the same place twice.
The apartment had all the amenities I needed, such as a kitchenette with a stove, dishwasher, and basic plates, bowls, & utensils. The doorman Frank was friendly, and the hosts communicated promptly whenever I had questions. I was traveling solo, but it would be great for a couple as well (though it might be difficult for 3 or more people).
Great place, in a great location!