Catarina's place is highly recommended. Location-wise it is right in the middle of Lisbon, 300 meters from Avenue da Liberdada. The flat was very convenient for 4 person and the A/C (in every bedrooms) came very handy too. Be aware that you have to walk uphill from the Avenue and that the apartment is on the 3rd floor and there is no lift. I was aware of these so it didn't came as a surprise.
Overall, I was very satisfied with the flat as it had all the necessary amenities and Catarina was flexible with the arrival and departure times. Furthermore she responded very quickly every time. In terms of price, the apartment provides a great value for money and ideal for families or a group of friends. The subway station is about 5 minutes walk. There were many brochures out on the table with useful tourist information.