Fantastic location, everything you'd need for a home-base from which to explore Madrid. Most major attractions are within walking distance although the Opera metro stop is a 2 min walk. Check google maps before deciding, often the estimated travel time was the same for the subway as for walking. Tons of restaurant options, nice way to sample dishes from every region of Spain. Some really good Peruvian, Venezuelan, and Cuban restaurants too.
Upstairs bed is a little on the small side, but both of us slept very comfortably. If you're out late like a local for tapas and a paseo around the neighborhood, sleeping in late isn't hard as the home is equipped with some nice black-out pull-down shades.
Washing machine is nice as it also dries the clothes. No laundry detergent, though, so maybe plan to pack or buy some soap pods.
Wish we could have stayed longer!