We stayed there three times, in a two bedroom apartment, throughout a month long trip in Spain. Fantastic staff, very well mannered and always ready to assist your every need. Extremely comfortable apartments, very new (opened in November). Great A/C amidst the summer heat, nice rooms on the smaller side (as is customary in Europe), Great blackout, very well equipped. Has a washer, but no drier, which might be my only issue. Very comfortable beds, plus great pillow menu Apartments are very soundproof.
Fantastic location (couldn't be better) in Fuencarral, full of shops, very close to restaurants, attractions etc. Apartment is in a pedestrian street but a few steps of Valverde through which traffic is allowed, Only 1 1/2 block to the center of the Gran Via, few more blocks to Puerta del Sol. Still very quiet, despite its location.
If you are coming from the airport, ask them for transportation ahead of time. There service is inexpensive with extremely reliable, courteous service in a Mercedes van.
Should we go back to Madrid, we will definitively stay there. Very highly recommended!