We stayed for a month at Ana's place and it was perfect - a super comfortable, spacious and stylish apartment with a lovely terrace to make the most of the summer evenings. As keen cooks we also loved the well equipped kitchen.
Belém is well connected to the city and the Lisbon coast, has good restaurants and sights of its own (not to mention the pasteis), and is great for relaxing walks by the river and watching the boats pass by. The apartment is therefore a brilliant base for exploring all that Lisbon has to offer.