Gianni's flat is perfect for a short or long stay. I've been there for a month and everything was perfect. The flat is adorable, and the location is great, super central and at a walk distance from Puerta de Sol and Atocha station.
Everything you need is close by, included several supermarkets.
Communication with Gianni was excellent, he was very kind and available to help.
Highly recommended for your stay in Madrid.