I had a conference in Barcelona and stayed at Javier's place which was a 15 min walk from the convention centre.
The apartment is located close to a large shopping centre and surrounded by bus stops that would drop you at main attractions within 30-40 min. It is also close to a number of metro stations. The beach is 5-10 min walk from the apartment. The apartment looked exactly like the pictures and was very clean. Javier was kind enough to book me a taxi to the airport during my last day. Highly recommended!