We went to Madrid for a long weekend for a friend's wedding. Instead of taking a room in their recommended hotel, we chose to stay in Oscar and Vanessa's flat (it was our first time using airbnb). We didn't regret our choice! Super clean, modern flat. Excellent location - litterally 2 min walk from the tube station Anton Martin and less than 10min from the Reina Sofia Museum (the one with Guernica) and also the park where you can go running.
The flat is super well equiped (washing machine, iron, microwave, etc).
Oscar was very helpful giving us a map with all the hot spots nearby and being flexible for check in/out.
Highly recommended!!!
ps. Madrid is fantastic!