I've been spending 5 weeks in Paulo‘s apartment and can highly recommend it for any kind of stay, wether short trip or longer business stay.
It's perfectly equipped, nicely furnished, clean and comfortable. Even though it's located in the heart of Bairro Alto, it's still a quiet place if you're looking for more relaxed days in Lisbon, or need to work e.g. from your laptop.
Paulo is very helpful and friendly, and very considerate that you're days in Lisbon become great memories.