We stayed at Sonia's place with our two kids for a month and really loved the place!
The location being in Alfama is amazing as you get to experience the old town right as you step out of the apartment. It's within 5-10 minutes walk down or up to two of the best views in the city, and near the castle. It's also inside a quite alley to provide some space away from tourists.
It's on a hill so be prepared to walk up the hill when returning for the night, but it's within 5-10 min walk from the nearby elevator that takes you down to the Pingo Doce Chão do Loureiro grocery store and further down via Elevator Castelo that can also be used to bring you up the hill and save you a lot of hiking. Another Pingo Doce is an easy walk up the hill, one that we frequented during our stay.
Communication with the host is easy and Sonia is very attentive. The washer, one of the beds, and some pans were abused by the prior renter and Sonia took care of them as soon as she could for us. The unit was nicely renovated and furnished very tastefully.
Only small negative is the neighbors upstairs seem to get into loud arguments quite frequently (during the day and night) that disturbs some of the peace of staying at the wonderful place. The fridge is also on the smaller side with a tiny freezer area but we still managed to cook several meals with the nice kitchenette.
We would definitely recommend any renters visiting Lisbon to consider Sonia's place and would love to return to it in the future if we have the opportunity!