Paula is a great hostess. Very welcoming and friendly and her local advice you must use...totally accurate. Ask her about the great fresh pasta restaurant (very cool young people run it) and the excellent seafood bar - do eat the amazing clams. Her apartment is only an easy 5 minute walk to the best Metro (Green) line into the city (and airport). The patio is even better than in the photo, and great to chill out on (its in shade in the afternoon) after walking Barcelona, having a cold drink before going out for nightlife. The neighbourhood is safe and quiet, with a supermarket close by.
You wont get better value for money anywhere else.