I cannot recommend this apartment enough!
It was located in the most perfect spot for our needs, close to local bars, shops and restaurants. There was a lovely coffee shop round the corner, each morning we visited and could get a fresh fruit smoothie and breakfast pastry for around 3 euros.
We were within a 2 minute walk to the metro station.
However, could walk to some places without use of the metro.
The apartment was simple, spacious and clean. Complete with everything we may need. We were greeted on arrival and shown to the apartment - this was a lovely touch.
Whilst we were there the lift was out of use (the apartment is on the 8th floor - not ideal with no lift!), we messaged the owners in the morning to let them know, he apologised for the inconvenience and assured us he would let maintenance know. By time we returned to the apartment that afternoon the lift was fixed. The host is extremely quick with responses, and extremely helpful.
If I were to return to Barcelona, I wouldn't dream of staying anywhere else!