I stayed in Madrid for 1.5 months for work and really enjoyed Barbara's place.
It is centally located close to Plaza Santa Bárbara and Chueca, where you can find lots of restaurants and cafes.
Gran Via and Puerta del Sol can be reached in around 30 mins walking or even faster by taking the metro.
The flat itself is very nice and beautiful.
It is decorated in a very elegeant way and big enough to accomodate 2-3 people.
The flat has everything what you might need.

So, I can totally recommend this place either for a short tourist stay in Madrid, but also for longer time for for a business trip, etc.
Barbara is a very nice host who quickly reacts to messages and is ready to help.