During my visit in Barcelona I left my room in the center of the city to spend some time in a distance of the most turistic area and Mario's place is great for that.
Subway stop is very close to his flat and the shop is on the way to this stop. I recommend nice places near his place like Parc Guinardo, Parc de la Pegaso and cool place called Nau Bostic - old factory? with very good graffiti arround.
Mario is nice and polite as he wrote on his profile and very helpful, he gave me a few of good advises. And room is comfortable and clean. It is very nice place and I recommend it!