The apartment is very nice and cosy, and most important, it is located in the city centre, thus you can walk from there to any place you would like to visit.
We really enjoyed our stay in Kristian's apartment. He greeted us so nicely showing us where to go and how to reach the main tourist sites (museums, gardens/parks,cathedral and so forth), and at last, he also took us out for amazing tapas (for locals) and cañas/copas making us feeling the "Real" vibe of Madrid at night.... We definitely recommend it!