We stayed at Toni’s place for a week. Though there were a lot of things to leave a positive comment about, I believe the location deserves to be mentioned first. It was quite central and close to everything we needed - places to eat and drink both casually and formally, to walk around and to grab a taxi whenever we needed it. The street itself was very quiet and easy to access.
The apartment was tidy and had everything we needed for a week-long stay. I would say it could cover a longer period as well for most of your needs. We also appreciated the tips from a local during our check in as they helped us later on.
Overall, I believe I can recommend this place for anyone looking for a place to stay at during their visit to Barcelona. :)