I really liked staying at Carmen's. It's very spacious for a one-bed apartment, with a big open plan living/kitchen area. It was also very well equipped with anything you may need if you wanted to stay/eat in. If you're planning on eating out, there are so many cafes, bars and restaurants as soon as you step out of the flat, and it's very convenient for walking everywhere, plus close to a number of Metro stops.
Madrid can be noisy at night - it's a busy city - but despite the number of restaurants near by, I didn't notice any noise, and the bedroom is at the back of the apartment which made it quiet.
Carmen was the perfect host. Her English is excellent and she was clear and prompt with all communication, and very thoughtful. She knew I was learning Spanish so leant me some grammar/teaching books. She was also brilliant when I left my phone in a taxi, and helped me track it down and get it delivered back to me. Such a relief for me, and probably a nuisance for her, but she was very amenable about it!
A great place to stay in Madrid. Gracias Carmen!