This Airbnb was my home for over a month and I would recommend it highly. The location of Xavier's place is very central - just outside your door you can find many restaurants, convenience stores, attractions (the Casa Batllo is a 3-minute walk away), the pharmacy is across the street, and the main shopping area is only a few minutes away. It's also very close to the Passeig de Gracia metro system - you really can't go wrong!
In addition, I loved the place itself. My experience as a solo traveler in the building as well as the location was very safe. The neighbors were extremely friendly and welcoming. One thing about the apartment is that the walls are fairly thin (I could hear my neighbor coughing or playing music), however, it did not bother me so much and most importantly did not interfere with my sleep. :)
I would recommend this place for 1-3 people. The decor is beautiful, very clean, and modern. And the bed is so comfy! You will find everything you need in the apartment for a month or so. I also liked how communicative and accommodating the host was. Overall, Xavier's place is awesome, I would stay here again next time I'm in Barcelona!