We were 5 days in Lisbon. The apartment was nice! with more than 100 years of history. Joana is a really kind person, always worry for you stay ok. The apartment is not too far to visit Alfama or Praça do Comércio (15-20 minutes by walk), and you have place in the street for your car, so you can use it to visit Sintra, Cascais or Estoril.
In fact, the apartment was clean, cheap and I thing even 5 person fits.
I recommend this apartment for your stay in Lison!