The apartment is truly amazing, just as on the pictures. It really has a warm atmosphere, is stylish, clean, well furnished and has a lot of amenities in the kitchen, too.
It is in walking distance from practically everything in the center, and next to Bilbao metro station, so public transport is also a quick option to get around.
Luis was a great host, he waited for me personally at the check-in, explained what is where in the apt, gave me some tips and recommendations to the city - so it was more than I could wished for. I can only recommend to stay there once in Madrid.