This apartment is in an ideal location for all of the major sights and we highly recommend. Yes, the five flights of stairs aren't for everyone but they did not bother us at all. Plus Tiago insisted on carrying our luggage both up and down. He was a wonderful host and even escorted us to a taxi when our phone data didn't link, which prevented us from summoning an Uber to the airport (Lisbon is a wonderful city for Uber and we strongly recommend).
The apartment is mostly quiet due to being on a high floor although there is always going to be street noise in the center of a city. It was extremely clean with all of the comforts of home (nice bedding, good shower, flawless wifi). The espresso machine was a treat, as were the port wine and pastries that Tiago provided. We will be back.