We stayed (a family of 6) in Maria's home for a week and had the greatest of times. It was winter and being able to enjoy Sevilla's sun in such a period was a bless. Maria's house is spacious (huge actually) and Maria was extremely welcoming, warm and helpful. Note that the house has 8 rooms, and even if we had 2 private bathrooms for ourselves, you might cross some other guests in the corridors.
It is very centrally located, 5 minutes by taxi from the train station and a 10 minute walk from the beautiful Plaza de Espana.
Everything was great!