Great apartment literally right across the street from the entrance to Atocha, so if you’re riding the train it is very convenient.
Smart check-in was a little weird because there were many steps, but there were detailed instructions so it was fine.
While you can’t hear the street noise, this unit is in a “cluster” of 5 other Airbnb units connected by a tiny vestibule - it’s like a big apartment split into six small units. This was fine, but you could hear everything going on in the other units quite clearly - I could hear and understand clearly what people in other units were saying.