The apartment is cozy, nice and clean. It's even more comfortable than I expected, because of many nice, homely details. During the day the traffic makes quite much noise, because the apartment is at street level, but during the nights it did not bother me at all. It's also quite easy to get to major sights in Madrid by public transport from the flat.
Veronica is very fast in responding to messages and all went smoothly, but she does not communicate in English. So luckily my data connections were working, I had access to Google Translate and also some Spanish friends to help me. But if you don't speak Spanish, make sure you have some sort of communication help available to handle the practicalities if you choose this Airbnb.