Belen's place was great! All the reviews saying that it was centrally located are accurate. She's a stone's throw away from the main museums, the city center, a major train station for day trips, and about a 25-30 min walk to things like the Royal Palace. I didn't have to take any subways or taxis at all.
The bed is very comfortable, the street is quiet, and the apartment is very clean.
Belen is very nice and helpful. We spoke at times and she would give tips (or we would just chat in general) but she also gave me space when I was tired and needed to wind down.
No complaints here - all good! Don't hesitate to book.