Summary: great place to stay at if you want to be close to Sagrada Familia and that part of the city. We had a great time staying there and had no complaints of any kind.
Host: the host was great. Very professional, responded to all our inquiries promptly. The host provided information about nearby attractions, current events and fun things to do in the neighborhood, as well as local restaurants. The host even stored our luggage on the last day after our check-out and before we had to go to the airport.
Pros: The apartment is close to Sagrada Familia, Sant Pau hospital, Park Guell. If you would like to stay in that part of the city, then this apartment is great place to do that. Within walking distance of all the attractions of that part of the city (including the local brewery). The apartment is very clean, has most needed amenities. The shower works great, the bed is good too. The balcony is the place's major selling point; the view is fantastic, the balcony is large, well furnished and has a deployable canopy to protect you from the sun. Great place to enjoy your wine at the end of the day. The building has an elevator, which is awesome, since the apartment is on the top floor. The soundproofing is great, you don't hear any outside noise, you don't hear any of your neighbors, and, if you are looking for a quiet relaxing evening and a good night sleep, this place will work well.
Cons: The apartment is relatively small. Single room with a balcony and a small bathroom. It will work well for a single guest or a couple, but most likely will be too small for a couple/group of friends, as there is no sufficient privacy. This part of the city is more residential than tourist-y; so, the number and quality of restaurants in the area is not as high as it is in other parts of Barcelona. Some of the host's recommended restaurants were closed (either permanently or temporarily), and some of the restaurants in the area open very late in the evening (so, be prepared for that).