Me and four of my friends stayed at Sonia's place for a week in August 2016.
Sonia's place was very nice. Although maybe a little small for 5 people. Only one person fits into the kitchen/bathroom but that didn't bother us that much. The walk up to the apartment was really exhausting, especially with luggage or shopping bags. All in all the apartment was clean, nicely furnished and really well located. It only takes 10 mins to the beach with bike and there's a little rental place in walking distance from the apartment!
Sonia was a great host who equipped us with a lot of recommendations on where to eat and what to see in Barcelona.
We loved every second of our trip and we would totally come back any time!