This is a gem of a space. Clean, large, and accommodating. Central AC was incredible in the summer heat. Tapas bars right outside are good, Atocha is walking distance even with luggage, there's a supermarket across the street, and the kitchen + family room are great.
Everywhere was either a nice walk or a 5-8 min cab ride away (and cabs are so numerous, cheap, and accepting of cards that Uber is less convenient). I highly recommend this as a base to explore Madrid.
A few things to be mindful of that don't impact my 5* rating:
1. The bedroom by the door hears all the noise of the old elevator. It's only bothersome before midnight and in the morning after 8, but we managed even as light sleepers. The far bedroom doesn't get this noise.
2. The pots and pans are very worn out and scratched up, so most of them are not safely usable. Pedro will hopefully get these replaced.
3. Garbage has to be taken out after 8:30pm But before morning. So when you're checking out, you have to consider this. I ended up taking a small bag to a public bin in the morning.