My wife and I stayed at this rental for four weeks on a working vacation. It is located in a busy part of Eixample, but the windows keep the noise out. It is near many excellent restaurants and cafes, is close to the metro, and within easy walking distance to the Barcelona Sants train station and Camp Nou (if you are a futball fan).
The check-in process was excellent. The unit was exactly how the photos depicted it: everything is in great shape, the bed and bedding are very nice, and the kitchen has all of the basics for cooking. The place is a little bit small but the price is fair given the location and the price for larger rentals in comparable areas of Barcelona. The downsides are 1) the wifi was too unstable for two people to be on simultaneous video calls, 2) the wifi signal does not reach the office space in the bedroom which renders it unusable, and 3) the owner across the hall was often partying late into the night (not sure if this was an isolated incident).