PROs
Alberto is an excellent host, friendly and responsive. He lives in the same apartment, but you get a very private two rooms, accessed by a lockable door (you still need to share the kitchen and toilet though). There's a double bed, a single bed, and a futon. The apartment is old, but the elevator works fine, there's hot water and the beds are reasonably comfortable. You can use the kitchen for cooking, store some goods in the fridge, and come and go as you like through an individual set of keys.
What's best about this listing is the location, which is halfway between Plaça d'Espanya and the center of the city. You're smack in the middle of one of the hippest restaurant areas, where approximately two million eateries per street offer mouth-watering dishes at good prices. Regarding connections, a ten-minute walk will get you to the center, and the metro (three blocks away on the Gran Via de les Corts Catalanes) will take you quickly and cheaply (get pre-paid tickets) anywhere you want to go in the resplendent city of Barcelona.
CONs
Barcelona is NOISY, and if you're looking for a good night sleep you will not find it here—that's the downside of staying in such a central spot. There's literally three restaurants four stories underneath your room, and Barcelonians holler, whistle, and cheer until deep into the night. Cars stop at the red light and showcase how loud their sound system can go, and dog walkers recall their dogs at the top of their voices at 4 AM. Not the host's fault.
BOTTOM LINE
Very recommended. Great host and phenomenal location at a reasonable price, but remember to bring lots of earplugs. Many thanks, Alberto!