I can highly recommend this location!
Goncalo is a wonderful host who really takes care of his guests. He makes sure that everything is fine and additionally gives you tips about places or restaurants you could go to. If you need help, just ask him and he will answer immediately.
The apartment is very stylish, perfectly clean and you've got everything you need. It's situated very central, so a lot of shops, bars and restaurants are right on the doorstep. Bairro Alto is known for it's nightlife, but still it's very quiet inside your room at night.
Overall I had a perfect stay in Lisbon and will definitely come back!