Gonzalo's appartment is really nice and comfortable with everything you can need for a few days in Lisbon, and especially a very cosy bathroom.
Its location in Bairro Alto is in the middle of the city's nightlife, with dozens of bars and restaurants all around, 5mn from metro Baixa Chiado. This is where all kind of people meet, from local students to tourists... including drug sellers and cops, a few meters from one another. You need to get used to that, but we never felt unsafe any second. Despite the busy streets, the windows are good enough to provide some good sleep in a calm environment.
It was a great experience and Gonzalo and his wife were really understanding with excellent communication.
I definitely recommend renting their place !