Minerva's apartment is superb. It is evident that a lot of care and thought has been put on the place. Everything is intuitive and nothing is missing to have a great time, it feels like home right away. The balcony and the traditional construction style is a highlight.
Poble Sec neighborhood is nice, with lots of tapa places and active nightlife (but still peaceful). You can walk pretty much everywhere, but if you don't want to, you still got metro stations nearby. I would recommend the apartment for sure, and would love to come back someday.