Let me start by complementing Filipe on his hospitality and his sense of humor.
The flat is located in a very convenient location on the Red metro line, a few stops from the airport to the north, and only one stop away from the green line which allows quick access to the historic central districts of Lisbon. The metro station is literally a minute away. Various bus routes are also available all around the apartment block. Airport, trains, busses, and fairies are all accessible via metro from this location. There is a grocery store directly across the street, with various other shops and cafes nearby. The flat included everything that we needed and served us well as a base to explore from. The flat is modern, well-equipped (clothes washer, dishwasher, microwave, espresso machine, television, wifi - there was nothing that we felt we needed and didn't have). The flat is fairly large, with one bedroom, a full kitchen, dining room, living room, bathroom, a small room for drying laundry, and a small balcony with a nice view over the city to the river below. I have nothing negative to say about the flat, the building, the location, or host. our expectations were exceeded! This was our first trip to Lisbon. The flat served as the perfect base to come back to each night to cool down and recharge for another day of exploration. All points of interest on our list were easily accessible (Sintra and Cascais by train, Obidos by bus, all Lisbon-specific locations were easily accessible either via metro and walk or via bus, and lastly a day on the beach via bus as well.
Also of note: Multibank ATMs are available (2) inside the shopping center across the street just outside the Pingo Dolce grocery store.
This flat was perfect for us. We liked having a place where we could go at the end of the day to wind down. We wouldn't have wanted to be in the center of the city. It was quiet and offered everything we needed. I highly recommend this flat and I truly appreciate the professionalism and friendliness displayed by Filipe!
Also - When you arrive at the airport, you should go to the metro station at the airport. There, you can purchase a Viva Viagem metro card (.5 Euro for the card) and put at least twenty Euro on the card. One card is needed for each passenger, but the card will allow access to the full metro, bus, and fairy system, as well as on trains to Cascais and Sintra. You can add more to the cards in metro stations as needed. We were in Lisbon for 12 days and spent about 35 Euros per person via our Viva Viagem cards. We used them every day.
Do some research before visiting the city - try to have a list of things you'd like to see and do while visiting. I recommend scheduling a walking tour for the first day so that you can get your bearings of the city and learn a little about the history and culture.