Very pleasant apartment in an excellent location, just a couple of minutes from Callao metro. Well equipped, clean and cosy.
It was quite noisy on the street outside at night but this didn't bother me at all.
Worth remembering that all of central madrid is quite lively until the early hours.
Check in / out arrangements were simple and easy.
The toilet is electric and doesn't take paper, which can be hard to remember!
overall I would recommend this apartment.