My girlfriend and I had a wonderful stay at Edu's place. The apartment is very central, you can reach everything in the downtown area by walking, and for farther places, there's Urquinaona Metro downstairs and many buses leaving from the square. Barrio Gotico starts right downstairs. Plaça Catalonia, which is one of the main squares of Barcelona, is one block away. Over there you have Hop-on-hop-off buses, AeroBus to the airport, a big Metro hub, shopping, North end of La Ramblas, etc.
The apartment itself is very modern, it was shining clean when we entered it, and it has all the needs without feeling cluttered. I could not have decorated it better myself :)
Edu himself was really helpful. He gave us lots of suggestions and recommendations, such as what to visit, where to change money, etc. Very friendly, excellent English, and pleasant to communicate with (Disclaimer: we communicated solely through SMS and AirBnB chat, although WhatsApp would have also been an option).
Word of advice: do not come with a car if you can help it. Nothing specific to Edu's apartment, but rather to Barcelona Downtown: it is almost impossible to find parking, and if you make the mistake to get into the narrow streets of Barrio Gotico, you'll have tough time getting out :) The public transportation will get you pretty much anywhere, and if you get a Daily or a 10-trip card Pass (they cover both Metro and Bus), for fairly little money.
Overall, a great experience, I'd strongly recommend Edu's apartment to anybody, and I'll surely hope it is available for my next trip to Barcelona!