Bairro Alto is a fun, but very VERY noisy part of Lisbon. Don't waste your time in Barrio Alto if you want to sleep--lots of people shouting/chanting until 2-3am every night. It's crazy.
The apartment is really good. It is small, but has kitchen, shower and nice little balcony. Neighbourhood is great for food. Hosts are very responsive with clear communication and great suggestions for restaurants (via messenger as we never met them). For other people it would be a good pick, but not for us.