Stayed at Alexandre's apartment for 3 nights with 3 other girls. It is a gorgeous apartment, loved all the decorations and little details that shows that a lot of thought was put into the place. It was well-equipped with all the necessary machines, condiments, pots, pans etc. Oh and Alexandre was really sweet to greet us with a bottle of wine & chocolates!
The location was extremely central (walking distance to the main square as well as the castle up the hill). Neighbourhood can get a little noisy at night but it didn't bother us & we were able to get decent nights' sleep (after catching back-to-back episodes of Castle on AXN - yay for cable TV!)
Size-wise was just right for 4 girls on a short stay. The day bed expanded to a really huge and comfy double bed. Sheets, towels and a blanket all provided :)
Leading up to the 3rd floor apartment was a long flight of steep stairs which may not be ideal if you have heavy luggage but thankfully Alexandre was very willing to help us. Other than that it wasn't a problem but may be an issue if you travel with elderly etc.
Lisbon is a lovely rustic place, we had fun just wandering up and down alleyways. If you have the time, consider taking a day trip out to Sintra to see Moorish Castle & Pena Palace! It's easy & cheap to get to from Rossio Stn and the sights are breath-taking :)