We had a great time at Sonia's apartment. It is very bright and welcoming, a cosy place to come back to after a long day of gawking at Barcelona's splendid architecture, or enjoying its bustling nightlife. Sonia is a really nice person and reacts very quickly to any question.
Moreover the flat is extremely well located; we toured many of Barcelona's major highlights on foot from there (Sagrada Familia, Ramblas, Barrio Gotic, etc.)
We would be glad to come back !