My friend and I stayed in Joao's modern apartment for 3 days and we loved it as it was very clean and tidy. Although we didn't get to meet Joao personally, we met his friend Pedro who showed us around the apartment.
The apartment is a short walk (less than 5 min) from Avenida metro station, so it is very convenient if you are ariving in Lisbon by air, train or bus. All the main tourist sights in the city centre are within 15-30 min walk from the apartment.
We strongly recommend this apartment to anyone who wants a quiet stay in Lisbon and yet is close to the city centre.