Our stay at this apartment was marred by the fact that the upstair neighbour was renovating his flat; consequently, 4 days out of 6, i.e. from Monday to Thursday, we were waken up by construction noises which started around 8:00 am. This pretty much took out all the fun of having our own place and managing your schedule on our own terms. At least in a hotel we would have had the possibility of getting another room or going to another hotel. With this Airbnb rental we were stuck in the construction zone! The owner of our rental told us she did not know about this situation and profusely apologized; it was a nice touch but did not make the noise disappear nor made our stay more pleasant.
This being said here are the pros and cons of the apartment:
Pros: modern apartment, clean, well appointed, with firm but comfortable mattresses, efficient air conditionning, fairly well equipped kitchen, dishwasher and washer. Within walking distance from many touristic attractions (Castelo São Jorge, Sé, Chiado etc.) as well as the important "praças" such as the Rossio, the Praça de Figueira, Martim Monitz etc.
Cons: while not as busy as other streets in the centre of Lisbon, the São Lazaro street is not really quiet at night. The traffic is fairly constant and the proximity of various businesses, i.e. 2 or 3 cafés, 1 mini market and one pizzeria-leitaria (which closes around 2:00 or 2:30 am), makes it impossible to sleep with the windows open; moreover, even with the windows closed and the air conditioning on, light sleepers might want to use ear plugs. Apart from this only a few things: (1) it would be nice to have some sort of sheer drapes in the bedrooms windows to let the light in while keeping some privacy since these windows look on the street and, once the shutters are open, there is not much between you and the passerby and (2) a toaster would also be nice.
In closing I should point out that the check-in process was very smooth and that, upon asking, we were allowed to leave our bags in the apartment a few hours before the check-in time. Communications with the owner were easy and without delay