Carlos is Great!
Everything was better than expected. Location is superb: walking distance to everything you want to see in Madrid, close to T (to-from airport), window and balcony opens in a small enclosed courtyard - not a great view, but it's quiet, no street noise at all in the middle of a city.
Carlos helped in any possible way, starting with being flexible on check-in/check-out time; when we arrived there was food in the fridge for us: cheese, jamon, yogurts, milk, fruits besides some crackers, cookies, cereal, etc.
You have everything you need in the bathroom: shower gels, shampoo, conditioners, toothpaste, cremes, can't list all.
Carlos was willing to help in any way, replying to any questions and asking whether we need any help. Best host I've ever had.