We rented Antoni's place because we wanted to spend some time in the city center in Barcelona. We were very much aware of the fact that the neighborhood is not the nicest or cleanest in Barcelona, and also that buildings are very old, but it worked fine for us. And that was the case, the building always smelled of something weird and the stairs are super narrow and low ceiling (be mindful if you have suitcases). Of course, if you are not aware of these things, you might want to do a search first to get informed so you don't set unreasonable expectations about the place.
However, the studio itself is very nice and completely different from the surrounding. It has a nordic flare but with a Barcelona touch - I would recommend it for short stays. Antoni is very responsive and the flat is very stylish with everything you need to make your stay comfortable.