Overall, this is a great apartment in a wonderful location, just a few minutes walk to the metro, lots of shopping, restaurants, and scenic views. High quality interior. Beautiful kitchen and layout of the apartment. It was very clean when we arrived, with towels ready and the beds (both the full and the two doubles) made neatly. Be aware that this is a loft, and there are no full walls, just partitions, including with the bathroom (there is a door on the bathroom and to the toilet). If staying here with other people, make sure you're comfortable with each other, and with sharing private spaces.
The apartment is on the third floor (second (0,1,2) for my European friends) with a small winding staircase. It can be tough to get big bags all the way up, but Mohamed (who met us at check-in) helped with the lifting. With the windows closed, the apartment is pretty quiet, but as soon as the windows are open, you get the full sound of the neighborhood (great sounds, but people are up pretty late sometimes!).
You can't beat the price or the location for such a high-quality apartment.
One thing to be aware of, is that when going with this apartment, you're dealing with a rental company through Alex instead of a single person renting out a couple of places. This means you probably won't meet Alex, instead you'll have someone else meet you at the apartment, and you will need to coordinate that once you arrive in Barcelona. This can be a challenge if you are coming from outside of the country.
As mentioned above, overall a high quality apartment, and we had a quality stay!
Josh