I stayed at Silvia's apartment for a long weekend with my adult children. It was clean and beautiful, decorated with elegance and taste. It is perfectly located in Chiado, the best neighborhood in Lisbon, lots of very nice restaurants and cafés, artists and musicians, wonderful views, great atmosphere and very safe! The metro station is very close and both railway stations are within 5 (Rossio)-15 (Cais do Sodre) minutes walk. You can take a train to Cascais (lovely beach town, in 30 minutes) or Sintra (royal palaces, in 40 minutes).
Silvia was very nice and super helpful with our questions. We would most DEFINITELY rent her apartment again if we were to return to Lisbon.