I sincerely recommend staying at Esther's place. The location is great, not far from the airport and also not far from the city center. Metro station is only 3-4 min from the apartment.
Everything was as on the pictures - the room was nice and cozy, and most importantly clean, as the whole place was.
She is really nice, helped us with anything we needed.
Good to know - she doesn't speak English, but we understood each other what we needed on my really basic Spanish. I'm sure that we would find our way without knowing any Spanish at all.
If we ever come to Madrid again, her place will be our choice!
Thank you Esther for everything :)