Absolutely phenomenal stay, but as other reviews have stated - be ready for stairs. The stairs were only really tough upon arrival and when we left, but otherwise, the place could not have been better. Since you're off the main road and many floors up, it's quiet with the windows closed but still perfectly located in the middle of the city. Metro, tram, and train stations/stops are all within a short walk. Lots of shops, restaurants, and cafes nearby. Some construction noise in the morning but minimal with windows and shutters closed.
The apartment is exactly as advertised. Clean, classic finishes with an unbeatable location. Comfy beds and gorgeous sitting room. Communication getting in was friendly and efficient. 10/10 would recommend. If I ever come back to Lisbon this is the first place I will check.