Sandra's apartment was fantastic. Much bigger than expected and in a terrific location. It is close to everything we needed (metro, food, site seeing, etc.). I would definitely stay in the Bairro Alto area again (and in Sandra's place if available).
Other comments talk about the noise. We slept in the upper bedroom connected to the outdoor patio and with the fan on couldn't hear any street noise at all. We loved our stay in Sandra's place, and in Lisbon.