We had a beautiful stay in Lisbon at Diogo's place. He was extremely accommodating with our late check-in on the first night and was helpful in suggesting places to eat for breakfast.
The location couldn't have been better. We were a 1-minute walk from Bairro Alto (the best nightlife in Lisbon), 10 minutes walking to Rossio train station (train to Sintra) and 10 minutes to the train that takes you to Cascais beach.
TIP: The tiny bar right below the apartment is the best!! The bartenders are so nice and the drinks are the cheapest in the area.
Also, the restaurant across the street (Cabacas) has delicious typical Portuguese cuisine or lava rock steak and has an awesome atmosphere. It's always packed so put your name down on the list as you come home from exploring so your table will be ready after you've showered and gotten ready.
The only criticism is that the shower didn't seem to get cleaned once during our 4-night stay (and it's a shared washroom) and we sometimes had some trouble reaching Diogo. Not a huge deal.
Not recommended for those looking for a quiet sleep as the street can be noisy at night, however this didn't bother us.