The apartment is very large, yes, its a huge bed, comfortable.. small kitchen area, and bath/shower that hard to gauge the hot and cold fluctuations.
The location could not be better, around the corner you are in the middle of the action, of restaurants, plazas, and in front of the palace, where you should take the tour. I think it's best to stay a night or two, and-not just day trip it from Lisbon, that way you will avoid the crowds during the day.