The apartment, I felt, was very spacious for two people. I traveled with a girlfriend and our bedrooms were at opposite ends of the apartment. The kitchen was well stocked with a coffee maker, pots and pans (nice ones) and anything you would need to cook.
It was a nice place to come home and relax after long days touring around.
The location is amazing!! A few blocks from metro, shops, restaurants, pedestrian mall - walkable to the waterfront in 15 - 20 mins, castle and all the great older areas of Lisbon.
Note: the apartment is up a fairly long flight of stairs and if you have any disabilities/seniors, it may be too much for you.
The rep that met us at the apartment (Ana) showed up on time for check in and check out and actually offered to help us with our luggage. She was very informative about any of our questions as well.