I don't think there is a better AirBnb experience available in Barcelona. If we're lucky enough to visit Barcelona again we would book Sean's apartment without any hesitation.
While the apartment is great, Sean and his family are what made the stay a memorable one. They are very welcoming, friendly, and great conversationalists. My only regret is that we didn't stay longer to talk with them more!
Regarding the apartment, it is amazingly beautiful and Sean does a great job of explaining the building's history and intricacies of the interior design. Nothing I could write could do justice to the apartment's beauty, so I highly recommend you book a stay and see it for yourself.
The location is also great, a 10 minute walk from Park Guell, as well as a short walk from the La Gracia, a neighborhood packed with interesting shops, restaurants, and bars. There is also a train station right outside the front door which makes access to other parts of the city very convenient.
If you've made it this far into the review and still hesitating, stop thinking and just book it!