Isabel's place is great. Clean, affordable, quiet.
Well, maybe a little too quiet. The apartment is located about 30 minutes walking from the hustle-and-bustle of Madrid's Center, and to my dismay, the Metro line servicing the Puerta del Toledo neighborhood was closed for 2 months (until September 2nd).
If you're looking for an affordable little hideaway for some shut-eye while you explore the wonderful city of Madrid, this is your place.