Sergi's place is in a fantastic neighborhood. There's nearby tapas, groceries, sites to see, bars, and a whole slew of other things nearby.
For us, we arrived into Barcelona on the day pro-Catalonian independence politicians were handed jail sentences. As a result, the entire Barcelona airport and transportation into and out were shut down. We originally were supposed to meet someone for check in at 15:30 and we weren't able to get to the apartment until 22:00. Needless to say it was a long day and yet the person we were supposed to meet was able to meet us no matter how far off we were. They provided great communication about our status and theirs.
The place itself is nice with 2 bed rooms and 1 bath. The lights can be a bit dim but, the rooms get a lot of natural light from the two windows in the bedroom. Inside the apartment complex it's being renovated and can have some tight stairs. With that said, the apartment is on the second floor and it's not too bad to get to.
Honestly, my only real complaint about the place would be the lack of a wine opener inside the place. I don't believe that minor complaint should keep you from booking the place though as it is very convenient and relatively nice.