We had a great family stay at Elsa&Rui's place.
The apartment is cute and well decorated, and has all the basics you need for a good stay (coffee machine, fridge, some dishes, heater/cooler, hair dryer etc)
When we were there, the neighbors were a bit noisy and we were not able to use both showers at the same time, but this was probably temporary.
The place was perfectly clean and well prepared. It's also well located in a neighborhood that's becoming Arty/trendy, and well connected with public transport for main historical touristic areas.
For a nice typical breakfast or even lunch, stop 3 meters before Brick's cafe at 26 rua do forno do tijolo, the snackbar o abilio o elegante has wonderful homemade pasteis de nata and bacalau cakes and some other simple but typical and delicious delicacies. Le patron parle même un peu français pour info :)
Also don't miss the A vida portugesa shop on the way to Martin Moniz.
Elsa&Rui were also super responsive and helpful, and the airport pickup is so great!! Lisbon airport was closed for a few hours that day and our plane was late, but the driver kept in touch and came to pick us up minutes after we finally arrived.
We definitely recommend this place.