Elsa's apartment is in a great location! Walking distance to La Latina with all it's bars and restaurants and the Mercado San Miguel. About a ten minute walk from Chocolateria San Gines and a little further on to the cathedral and palace. We even walked to Retiro Park in 30mins. Aside from a return taxi to the airport (30 EUR each way) we didn't pay for transport for the whole weekend.
Elsa was full of great tips for bars and restaurants and provided us with a map of the city. The apartment is a great size for two people and is spotlessly clean. The bed is a little hard and the light from the corridor is quite bright but didn't stop us from having a great time. Elsa even stored our bags until 2pm, which was very kind of her.
All in all this apartment is great value for a money and is perfect for a quick weekend in Madrid.