We have stayed for a week at the end of April. The apartment is very well placed in Mouraria, close to Alfama, with all major objectives within walking distance. Uber from the airport costs about 10 EUR. It is a very convenient way of transportation in Lisbon!
Sandra and Carlos responded very quickly to our messages. We highly appreciated the complimentary bottle of wine, can of sardines and coffee! Thanks for hosting us!
The apartment, located in a very old building, is small and has basic facilities, but is ok if you plan to spend most of your time outside. As the building is old, it would require a better ventilation. The acoustic insulation is quite bad, you can hear the neighbours upstairs walking, talking and even snoring :) As there is no source of heating, it was a bit cold during the night. I would recommend it only for a short stay.
All in all, the value for money is reasonable, location is excellent close to the castle and the hosts were responsive.