Just a terrific place and great host. I didn't see Gustavo that much apart from my arrival, but everything was as described... and better.
The apartment is very nice, ample, and clean. The communication was always fast and smooth, and Gustavo received me with a big smile. I like to walk, so the location in a little hill was a plus for me.
It's about 30-35 min walking to the city center, but the apartment is close to the metro, and actually there is everything you could need around the neighborhood.

Definitely Gustavo's place would be my first choice on my next visit to Lisbon.