Lovely stylish studio in excellent location. Very central and lively neighborhood with plenty of bars and restaurants all around. Check in was perfect, very well organised.
The flat is very small (more like a hotel room) but this wasn't really an issue for me. Good shower pressure (always important for me). The only negative I would note is that the walls are extremely thin, I could fully hear the neighbours TV and conversations through the wall.
Overall this is a perfect place if you're looking for a central, clean and modern apartment for a weekend trip to Madrid.