Tiago's place is very close to Baixa-Chiado metro and it's great for exploring Lisbon. The place is really nice and spacious enough (two bedrooms). It was also very clean. We had a really smooth communication with Tiago regarding the checkin process. There were even some fruit, coffee and water in the kitchen -which is always appreciated.
Despite being in the very center, place is generally very quiet apart from some random noises, which shouldn't bother you though.
As others mentioned, apartment is at 5th floor and bathroom is a bit small, but these are not problems for me.