Amazing location. Could not be better. An easy walk to Plaza Mayor, Prado, Retiro Park, etc. And great tavernas and cafes and markets within a minute's walk. The location in Madrid could not be better.
The balcony is lovely with a great view and, on a bright day, is a nice spot to grab a coffee and catch your breath.
The flat itself is, to be fair, exactly as described. But do bear in mind that there is only one bedroom (through which you access the bathroom). The two other beds are fitted into alcoves with very low ceilings in the living area. They are separated by shower curtains that fall down at the slightest touch.
The kitchen is pretty basic but fine.
If you were a family or similar, I don't think this would work.
For us - a friend and I looking for a base to explore Madrid - this suited us well enough and we had a great weekend in this perfect location.