As many people have commented before, this apartment is really wonderful (exactly like on the pictures). It is clean, the kitchen is huge and well equipped, the living room has enough room for at least 8 people (we were 5), the furnishing looks really nice.
The location is very central, there are restaurants, bars, clubs and so on just along the street. Public transport is also really close by (metro and tramway), but you won't need it if you only want to travel in the city center.
Joao and Joana have been great hosts, the check-in was quick and they gave us both a comprehensive list of attractions and restaurants (we tried some of them, really good advice). They were always contactable, and even contacted us to ask how we were doing.
We really enjoyed our vacation in Lisbon and would love to stay at Joao's place again!