We had a great time in Madrid for 4 days. The apartment is located perfectly. You can walk or take the Metro to the city centre, but we suggest to enjoy the neighborhood. La Latina has a lot of beautiful places tot have brunch and tapas/canas.
Diego was very nice and responded quickly. We could leave our bagage before check-in time, so we could go enjoy Madrid.
You can take the airport shuttle to the city center or the metro to La Latina Metro station. 50 min (Line 8-10-5) for 5 euro. You have to buy a metro card, but you can use it every time you take the metro.
People don't speak much English in Madrid, but are willingly to understand you.