My friend and I had a great time staying at Xavier's place for one month. The only con was that there was some miscommunication upon arrival – we had to wait outside the door about 20 minutes before his sister came and helped us check-in. Prior to our arrival though, Xavier was quick to respond and he did notify us that he was out of town the date of our arrival (we switched our dates last minute as well).
The following day Xavier stopped by to formally introduce us to the apartment and answer any questions we had. He was accommodating and ordered us an iron board, hangers and new lightbulbs which arrived in just a couple of days.
Since it was just two of us, the apartment was spacious and comfortable. The kitchen was well-equipped with everything one may need for a month's stay. Nespresso machine, electric kettle, pots/pans, toaster, etc. We were also working remotely so having a desk and fast wifi was a plus.
The location was convenient for our needs - close to many lively bars and restaurants, as well as Port Vell/Barceloneta beach. We walked most places we went.
Note that the area can be noisy at night as you are in the center of a lot. Additionally, taxis cannot go directly to the front door of the apartment, so you need to walk a little bit if taking a car (this wasn't a huge issue in the end though).
We were so delighted with Xavier's apartment we would have stayed longer if we could!!