Pros: Great location, many restaurants and small grocery shops within a 5 minute walk. Also within a 10-15 minute walk to many Metro lines. Pretty, lively, safe neighborhood. Located in an apartment building, accessed by a key to the building and then a 2nd key to the apt (felt secure). Apt. is 1 level above ground level, and there is an elevator if needed. Apt is spacious, large combined living room/dining room, total of 3-4 bedrooms (4th has a futon, we did not use this room). The largest has a cute small terrace, nice to sit and read on. This room faces the street but was not too noisy at night. Room darkening drapes in all bedrooms. The apartment is very clean and well equipped.
Pau, the host, left us a basket of muffins, etc, and stocked the refrigerator with beverages. He met us at the apartment to give us the keys when we arrived. Pau readily communicated any time that I had a question, both prior to our arrival and during the stay. Best of all, he was nice enough to offer to let us stay as long as we wanted to on the day of our departure, which was so convenient because we were taking a flight at 5PM.
Con: There was a sewer-like odor in the apartment that we noticed starting the day after we arrived. To be fair, we did not contact the host to mention it, because we were really not in the apt very much-out and about exploring Barcelona of course! Sometimes it was mild, but when we returned to the apartment at the end of a day, it was rather strong.