We had an absolutely fantastic stay at Frederico's apartment and could not fault one thing about the accommodations.
We were delayed by about 2hrs getting into Lisbon and the concierge, Elsa, who checked us in was waiting patiently to greet us with a smile and some fantastic advice on what to do during our stay. The apartment itself is comfortable, quirky and equipped with all of the necessary amenities to ensure a smooth stay (kitchen stocked with cooking and crockery essentials, clean and comfortable bedding, clean bathroom, areas to relax and eat etc.). The location is also fantastic, just a stone's throw from Baixa-Chiado Metro station, and we had no problems navigating the city from this central base or finding our way back after a long day of exploring.
All in all this was the perfect choice for us and we would definitely recommend the apartment to anyone visiting Lisbon.