We were four in the flat and stayed for 3 nights.
It was everything just how we needed it.
The flat is super located, easily to arrive via Metro and short walking, but also Taxi is cheap everywhere in Lisbon (5€ = 10-15 min ride, if u pay more they fool you)
A supermarket is near, nice places to eat just down the road and Bairro Alto with its tiny streets just in walking distance.
We really had a blast in that city.
And João with its flat made it the most comfortable for us, especially with a nice welcome bottle of regional wine, which tasted super good. He organised somebody to welcome us just in time and both would have been available while our whole stay in case we had questions.
We strongly recommend to spend your Lisbon trip here!