We really loved the apartment - it was very clean, the kitchen is well equipped, and we enjoyed the little decorative touches.
We did not meet Sandra and Joao but met their colleague Dipa who welcomed us. Sandra and Joao were really helpful in the lead up and during our stay with good communication via Whats App and answered promptly if we needed anything. They also generously supplied us with some wine and supplies for the fridge at the start of our stay which was a lovely touch.
The apartment is in a small quiet street and but on a couple of occasions we were woken up in the night by people being loud/partying in the nearby streets but this didn't happen every night. As others have mentioned there are quite steep steps up to the apartment but this wasn't a problem for us, just may be worth thinking about for people with mobility problems. We also found that sometimes the hot water didn't last too long when we were showering - there was only two of us and I do wash my hair every day so others who take smaller showers might be OK! The apartment is about 10 mins walk from Cais Do Sodre train station and it's a pretty easy walk (though uphill) into Baixa/Chiado/Barrio Alto. Also a stop for the historic tram 28 is right at the end of the road! All in all we had a really pleasant stay and fell in love with Lisbon!