Cristina's flat is a great choice. It was clean, perfectly located (quite street, yet walking distance to Malasana, Chueca - 15 min, Prado 35 min, Atocha 45 min, metro 7 min, el Cort Ingles 3 min), there was everything one can need (from a milk-for-latte maker to toothpaste and Madrid map), snacks for breakfast, indeed as written comfortable mattress, and a big lovely terrace. Everything was in a good condition. Cristina was very helpful and quick in responding to messages. I enjoyed my stay a lot in general in Madrid and in Cristina's flat in particular :)