The apartment was just like in the pictures, clean and nicely decorated. We were in Lisbon for 8 days with 4 friends.
The apartment is located in Bairro Alto, which was perfect for us, because of the night life here. If you have trouble sleeping, it's not the perfect place to stay, but we didn't have any trouble with it at all.
We didn't meet Gonzalo, but we kept mailcontact. He is very nice and can tell you all the things you need to know about Lisbon. Next to that, he's very flexible regarding your arrival and departure. We could come earlier than check-in time and stay longer than check-out time (obviously this depends on arrival/departure of the other tenants).
Everything combined, our time in Lisbon was great and we would really recommend this apartment if you're visiting Lisbon!