A very nice apartment in a very nice neighborhood, with everything you need for a comfortable stay. I would recommend the apartment, with one significant caveat.
There is a nightclub underneath the apartment, and the street was full of people making a huge amount of noise between 3/4am and 6/7am on Saturday and Sunday morning. We were in the apartment for two weeks, and this happened on both weekends, and also on Xmas Eve and New Year's Eve, so it is safe to say that this will be a consistent issue for this apartment on any popular night for going out in Lisbon.
The main bedroom (easily the most comfortable of the two in the apartment) faces the street, and we were woken up every on every night mentioned above by the noise. It was impossible to sleep through, and the windows are only single-glazed so they do very little to keep out the noise. There is a second bedroom at the back of the apartment which is more protected, but anyone expecting to occupy both bedrooms over the weekend should know about the problems caused by the nightclub.