The apartment is really cute and very close to the center of Lisbon. Everything worked and was exactly like described. The bed is comfortable and the flat was really clean and tidy! We had a wonderful stay, and we would recommend the apartment to anyone who isn't afraid of steep stairs :D
Pedro's father (who handled the key exchange) is a lovely person, he was so nice and helpful!
In conclusion, this is a great apartment with really nice owners, so if you go to Lisbon: book this place! :)