Roberto's place is amazing. The location alone makes it perfect. It is a 2 min walk to Sol metro station, and from there the city is at your fingertips. The area is also extremely walkable, but the metro was nice to have after a long day of exploring or if your legs are tired.
As far as amenities, this place has it all. Great washer/dryer (we didn't use the dryer but used the washer a few times). The kitchen is a good size if you feel like cooking, The shower had good pressure and was roomy. Nice big towels, an AWESOME hairdryer...the list goes on. AC worked great (it was unusually hot while we were visiting), and the windows block out the noise from below (this is the in the Centro, so it was loud until late into the night).
We enjoyed sitting with the windows open and listening to the city below, we enjoyed the closeness to public transportation, and we especially enjoyed Roberto's hospitality. Don't wait, book this place and enjoy your time in Madrid knowing you have a great, safe place to call home while visiting.