Where to begin?! Both my girlfriend and I really enjoyed our stay at Mathilde's apartment. The apartment itself is spacious, clean, comfortable and well presented - you have everything you need there for a relaxing break.
The outside terrace is large and an excellent space for relaxing and unwinding after a busy day in the city, or for preparing to head into town. The views overlooking the city centre and wonderful and also looking further up the mountain and watching the sun disappear. The pool is clean and well maintained.
Hosts Mathidle and her husband are very friendly, easily contactable and available for any questions and queries you may have.
One thing to note is that the apartment is not central. However it is serviced by a metro station (15min walk to the metro, 15min ride to city centre). Taxis from the centre cost 15-20€ and are readily available so we didn't have any problem.
I would not hesitate to recommend Mathilde if you are looking for a romantic and peaceful place to stay in Barcelona, and I look forward to staying there in the future. We thoroughly enjoyed our visit!