First, while small, the place is great, and it's in a FABULOUS location - right in the heart of the Gothic area. Everything was within walking distance - the marina, Place d' Angel, the Arc d' Triomphe, heck, even Sagrada Familia if you don't mind walking a few miles.
Bed is comfortable - and since we were there in December, we didn't need the aircon, and we didn't need the heaters. Temps were perfect.
Having a washer was a definite plus, and having the private patio for drying the clothes was useful as well.
Carlos is a great host -- very responsive and accommodating. Very nice guy. Had fruit as well as water (still and gas) in the fridge.
My one and only problem with the place is the sewer gas smell in the building AND the apartment. I realize it's an old building, but it was really intense. Carlos poured some chemical down the toilet, which helped, but it never completely went away. I had to leave the bathroom window open the whole time, which made it less noxious. Running a load of laundry also seemed to help. If it weren't for this, I'd give the place 5 stars. The place is really in an excellent location, Carlos was great, the apartment is comfortable (albeit a bit cluttered for my taste) -- but I cannot, in good conscience, not mention the sewer gas smells. I rely on others' reviews when choosing a place on AirBnB so I am trying to be as informative as I can. If it weren't for that fact, I'd stay here again in a heartbeat.